Vapor-compression evaporation system and method

DIVISIONAL APPLICATION APPLICANT: THE TEXAS A & M UNIVERSITY SYSTEM Invention Title: VAPOR-COMPRESSION EVAPORATION SYSTEM AND METHOD The following statement is a full description of this invention, including the best method of performing it known to me:

VAPOR COMPRESSION EVAPORATION SYSTEM AND METHOD TECHNICAL FIELD OF "]'HE INVENTION The present invention relates generally to the field of evaporators and heat exchangers and, more particularly, to vapor-compression evaporation systems and methods.

BACKGROUND OF THE INVENTION Typical steam jet ejectors feed high-pressure steam, at relatively high velocity, into the jet ejector. Steam is usually used as the motive fluid because it is readily available; however, an ejector may be designed to work with other gases or vapors as well. For some applications, water and other liquids axe sometimes good motive fluids as they condense large quantities of vapor instead of having to compress them. Liquid motive fluids may also compress gases or vapors.

The motive high-pressure steam enters a nozzle and issues into the suction head as a high-velocity, Iow-pressure jet. 1[he nozzle is an efficient device for converting the enthalpy of high-pressure steam or other fluid into kinetic energy. A suction head connects to the system being evacuated. The high-velocity jet issues from the nozzle and rushes through the suction head.

Gases or vapors from the system being evacuated enter the suction head where they are entrained by the high-velocity motive fluid, which accelerates them to a high velocity and sweeps them into the diffuser. The process in the diffuser is the reverse of that in the nozzle.

It transforms a high-velocity, low-pressure jet stream into a high-pressure, low-velocity stream. Thus, in the final stage, the high-velocity stream passes through the diffuser and is exhausted at the pressure of the discharge line.

SUMMARY OF THE INVENTION According to one embodiment of the invention, a vapor-compression evaporation system includes a plurality of vessels in series each containing a feed having a nonvolatile component. A first set of the plurality of vessels includes vapor-compression evaporators and a second set of the plurality of vessels includes multi-effect evaporators. A mechanical compressor is coupled to the last vessel in the series of vapor-compression evaporators and is operable to receive a vapor therefrom. A turbine is coupled to, and operable to drive, the mechanical compressor. A ptwnp {s operable to detiver a cooling liquid to the mechanical compressor, and a tank is coupled to the mechm]ical compressor and is operable to separate liquid and vapor received from the mechanical compressor. A pinrality of heat exchangers is coupled inside respective ones of the vessels, wherein the heat exchanger in the first vessel in the first set is operable to receive the vapor from the tank, and at least some of the vapor condenses therein. The heat of condensation provides the heat of evaporation to the first vessel in the first set, and at least some of the vapor inside the first vessel in the first set is delivered to the heat exchanger in the next vessel in the first set, whereby the condensing, evaporating, and delivering steps continue until the last vessel in the second set is reached.

Embodiments of the invention provide a number of technical advantages.

Embodiments of the invention raay include all, some, or none of these advantages. For example, because the vapor flow through the compressors is smaltel; the compressors may be smaller than previous compressors, rEhe compression ratio may be adjusted so the compressor operates h its most efficient range. This is particularly important for a straightlobe compressor, which has better efficiency at lower compression ratios. Because multiple stages may be used in the vapor-compression evaporators, the compressor may be small, and compressor energy efficiency may be improved using liquid water injection.

Heat exchanger coatings may prevent scaling and thereby fadlitate art increase in the system pressure and temperature. This has the following benefits: (1) the compressor may he compact; (2) the compressor may operate in a more efficient region; and (3) many stages may be used in a multi-effect evaporator secffon. Heat exchangers may be easily disassembled to replace worn components, and the tusks and heat exchangers may be integrated hato a single unit. The channels fhat feed the heat exchangers may have a large flow area to reduce pressure drop, which increases system efficiency. A pipe allows the heat exchangers to operate at elevated pressures, and the sbeet metal heat transfer surfaces are inexpensive compared to tubular heat transfer, surfaces. The sensible and latent heat exchangers may be integrated into a single low-cost system.

BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the invention, and for further features and advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:

FIGURES 1 through 8 illustrate various embodiments of a vapo compression evaporator systems according to various embodiments of the present invention; and FIGURES 9 through 48 illustrate various embodiments of heat exchanger systems according to various embodiments of the present invention.

DETAILED Description In some embodiments, the technology described herein may be utilized in conjunction with the technology described in U.S. Patent Application Serial Numbers 10/944,071, t 0/944,374, and 10/944,31V, which are herein incorporated by reference.

FIGURES 1 through 8 illustrate various embodiments of a vapor-compression evaporator system according to various embodiments of the present invention.

FIGURE 1 illustrates a vapor-compression evaporator system 10 according to one embodiment of the invention. I_n the illustrate embodiment, system 10 includes a plurality of vessels 12a-f in series to form a multi-effect evaporator system. A multi-effect evaporator system operates at successively lower pressures and temperatures. Generally, steam from a higher pressure evaporator boils water in an adjacent lower pressure evaporator, t_a the illustrated embodiment, vessels 12a-f are divided into two sets. The rightrnost set of vessels 12a-c are called the "vapor-compression evaporators" and the leftmost set of vessels 12d-f are called the "multi-effect evaporators." Energy is supplied to the vapor-compression evaporators using vapor compression, and energy is supplied to the multi-effect evaporators using excess steam generated in the vapor-compression evaporators. A pump may be required to transport fluid from low to high pressure. To recover energy, a suitable turbine may be optionally employed when fluid flows from a high to low pressure.

Each vessel contains a feed 14 having a nonvolatile component, such as salt or sugar.

][he feed 404 may first be degassed by pulling a vacuum on it (equipment not explicitly shown); however, degassing may occur using a number of suitable technologies. For example, feed 14 may be introduced into a packed column operated at vacuum conditions.

To enhance degasshlg, steam may introduced into the packed column to sMp dissolved air.

Another degassing method may employ a hydrophobic mcanbrane, such that a vacuum on one side of the membrane removes dissolved gases but liquid cannot pass through.

A mechanical compressor 16 is coupled to the last vessel in the vapor-compression evaporators series (12c) and is operable to receive a vapoi therefrom. Any suitable mechanical compressor may be utilized. In the illustrated embodiment, a "combined cycle" engine, which includes a gas turbine 18 (Blanton Cycle) and a steam turbine 20 (-Ral kme CycIe) is utilized to power mechanical compressor 16. Waste heat from gas turbine 18 (as indicated by reference numeral 19) is used to make steam that powers steam turbine Mechmzical compressor 16 pulls vapors 5corn the low-pressure evaporator (12e) in the vapor-compression evaporator section. Liquid water, as indicated by reference numeral 21, is injected into mechanical compressor 16 via a suitable pump 22 to keep it cool, which improves energy efficiency. The liquid water may be saltwater or freshwater. Saltwater is preferred if mechanical compressor 16 may tolerate salt, otherwise freshwater may be used.

If saltwater is used as the injection water, a knock-out tank 24 is coupled to mechallical compressor 16 to prevent salt water from being entrained in the outlet vapors. The vapors produced from the evaporation of the injection water provide energy to vessels 12a-f.

A plurality of heat exchangers 26a-f are coupled inside respective vessels 12a-f. Heat exchanger 12a is operable to receive the vapor from knock-out tank 24. At least some of the vapor condenses therein, whereby the heat of condensation provides the heat of evaporation to vessel 12a. At least some of the vapor inside vessel 12a is delivered to beat exchanger 26b, whereby the condensing, evaporating, and delivering steps continue until the last vessel in the series is reached (in this embodiment, vessel t2f).

Concentrated product 30 may be removed from each of the vessels 12a-f. Energy that is added to system 10 may be removed using a suitable condenser 32. Altematively, if coildenser 32 were eliminated, the energy added to system 10 increases the temperamre of concentrated product 30. This is acceptable if the product is not temperature sensitive. Even though feed 14 is degassed, there often may be some gas that enters system 10. To remove nor condensibles from system 10, a small stream (as indicated by reference numeral 27) is pulled from each vessel 12a-f, passed through a suitable condenser 28, and sent to a vacuum pump (not shown). Condenser 28 may knock out water in the bleed stream, which prevents loss of water vapor and reduces the load on the vacuum pump needed for the low-pressure sections of vessels 12a-f. Low-pressure steam (as indicated by reference numeral 29) from the exhaust of steam turbine 20 may be added to the series of vessels 12a-f where the pressures of the exhaust steam and evaporators most closely match, in this embodiment, between vessels 12e and 12d. A plurality of sensible heat exchangers 34 may be coupled to vessels 12a-f for heating feed 14 or for other suitable functions.

FIGURE 2 illustrates a vapor-compression evaporator system 40 according to another embodiment of the invention. System 40 is similar to system 10 above; however, in system a gas turbine 42 and a steam turbine 44 each drive their own mechanical comNessor 46a, 46b. Compressors 46a, 46b are arranged in series so that mechanical compressor 46a is coupled to the last vesset in the vapor-compression evaporators series (vessel 48c) and is operable, to receive a vapor therefrom, while mechanical compressor 46b receives compressed vapor frown mechanical compressor 46a and delivers it a knock-out ta 1 k 49_ FIGURE 3 illustrates a vapor-compression evaporator system 60 accordion to another embodiment of the invention. System 60 is sh-nilar to system 40 above; however, in system the mechanical compressors 62a, 62b are arranged m parallel so that mechanical compressors 62a, 62b each are coupled to the last vessel in the vapor-compression evaporators series (vessel 64e) and operable to receive a vapor therefrom before delivering it a knock-out tank 66.

FIGURE 4 illustrates a vapor-compression evaporator system 80 accorcthlg to another embodiment of the invention. Systsra 80 is shnilar to system 40 above; however, in system liquid water is not injected directly into either mechanical compressor 82a or 82b.

Instead, an intercooler 84 is used that employs a packed column 86 that has liquid water, such as saltwater or freshwater, trickling over packed column 86. A demister 88 near the top of intercooler 84 prevents liquid droplets from entering the second compression stage, i.e., mechanical compressor 82b. System 80 also illustrates the elimination of a knock-out tank.

In this embodiment, vapor exiting mechanical compressor 82b enters a heat exchanger 90a in a vessel 92a.

FIGURE 5 illustrates a vapor-compression evaporator system !00 according to another embodiment of the invention. System 100 is similar to system_ 10 above; however, in system 100 an internal combustion engine 102, such as a Diesel engine or Otto cycle engim,e, is utilized to power a mechanical compressor 104. Waste heat from engine 102 comes from two sources: gaseous exhaust (as indicated by reference numeral 105) and the coolant that circulates through the cylinders. In one embodiment, the circulating coolant provides waste heat at approximately 100°C, which may be added to the multi-effect evaporators. The exhaust gases (105) are at approximately 800°C and may be used to generate additional steam for the mulfi-effect evaporators (in this embodiment, vessels 106e, 106f). Because the gas is very hot, it coutd potentially damage the heat exchangers t08e, t08f. Opfionatly, exhaust gas t05 may be sent to a packed column t08 with trickling water t09, which lowers the temperature by generating steam. A fuflher advantage of packed column ] 08 is that it may wash soot from the exhaust 105, wt ich could potentially coat the surfaces of heat exchangers 106e, 106f and reduce heat transfer effectiveness.

FIGURE 6 illustrates a vapor-compression evaporator system 120 according to another embodiment of the invention. System 120 is similar to system 100 above; however, system 120 employs one or more membrane evaporators 122a-c to replace some or all of the multi-effect evaporators. In the illustrated embodiment, membrane evaporators 122a-c each have three chambers. A pair of outer chambers 124a-c, t26a-c separated by an inner chamber 128a-c. Outer chambers 124a-c, 126a-c have saltwater flowing, therethrough and hmer chamber 128a-c has freshwater flowing therethrough. Outer chambers t26a-c are separated from inner chambers 128a-c by an impermeable membrane 130a-c, m d outer chambers 124a-c are separated from inner chambers 128a-c by a hydrophobic vaporpermeable membrane 132a-c.

In operation of one embodiment of system I20, feed water 134 enters outer chambers t26a-c. As feed water 134 flows through outer chambers 126a-c, the temperatm-e of feed water 134 rises due to heat transfer through impermeable membranes 130a-c. Feed water I34 exits outer chambers 126a-c and enters respective heat exchangers 136a-c where the temperature of feed water 134 rises by a few degrees (typically, between 5 and 10°C)o The heat required by heat exchangers 136a-c may come from any suitable source. In the illustrated embodiment, heat exchanger 136c receives heat from the last vessel in the series of vapor-compression evaporators (vessel 143c). Both heat exchanger 136a and 1361o receive heat from an engine i 4 2.

Feed water 134 then enters outer chambers 124a-c. Water evaporates from the hot feed water t 34 and flows through hydrophobie vapor-permeable membranes 132a-c, thereby condensing in inner chmnbers 128a-c. The water may then be collected as product water, as indicated by reference numeral 138.

FIGURE 7 illustrates a vapor-compression evaporator system 150 according to another embodiment of the invention. System 150 is similar to system 120 above; however, system 150 employs waste heat from a gaseous exhale t 52 of an engine 154 to make steam t 56 that is employed in the vapor-compression evaporators 158 a-c.

The above systems may use any suitable mechanical compressor types. For example, high-speed shafts from gas or steam turbines are best suited to drive centrifugal or axial vane compressors. Low-speed shafts from Diesel or Otto elagines are best suited to drive gerotor, helical screw, sliding vane, or straight-lobe compressors (e.g., Roots blowers). Straight-lobe compressors may be particularly attractive because they are inexpensive; however, straight tobe compressors are efficient only at low compression ratios.

FIGURE 8 shows the energy mass balances for an evaporation system 170. The basis of the calculation is 1 kg of saturated water vapor at Tj. The work required m a compressor 172 is (1) The compressor work may be divided into two portions: the ideal work requirements plus the "lost" work that is co 1 averted to thermal energy.

q (3) ]'he following Js an entropy accotmting around compressor 172:

Accumulation = Input - Output + Generation - Consumption(4) At steady state, 0 = + :a;,,)- 11+ &o, ÷ - 0(5) where T , is the average temperature of compressor 172 and must be expressed as absolute temperature. Substituting Equation 3 for Tto t and the arithmetic average for T :

(6) The following definition is made:

which may be substituted into Equation 6:

++s, o,÷ To solve for x, the amount of injection water that evaporates in compressor 172, Equation may be expanded as follows:

(9) From Equation 7, the definition ofk may be substituted into Equation 9:

The water m, produced by the vapour-compression evaporator 174 is:

,n,. = n (l+x) (11) where n is the number of stages in the vapor-compression evaporators 174, which may be arbitrarily selected.

The water m produced in the multi-effect evaporator section 176 is:

where ? T is the temperature difference in each heat exchanger of the multi-effect evaporator 176, AH '°p is the latent heat of evaporation of the compressor lifter, and A// y is the average latent heat of evapoIafion in the multi-effect evaporator 176.

The water mc produced iF the multi-effect evaporator ] 76 that uses waste heat fi-om the engine is:

no 2A£r,° p = AT ) 2A r'°p (13) /t is assumed that the waste heat is available as sensible heat (e.g., Diesel engine exhaust gas, hot gas from Rankine boiler). The factor of 2 ha equation (13) accounts for the fact that the waste heat Q, is available as sensible heat, not latent heat. Rather than transferring all the waste heat Q, at T, to the top evaporator, each evaporator receives 1/n,Q, in direct heat transfer from the waste gas stream. Effectively, this reduces the output of the multi-effect evaporator by half The total water mt produced is m, = m. + n%, + m (14) The high temperat-ure heat applied to the engine 178 is:

Qh :_ W = (1 + x) ' - (!-?T "p + x ja) (15) r/€ r L r The specific heat requirement is:

(3.

Specific Heat Requirement is = -- (16) 77 € and the specific work requixemertt is:

W Specific Work Requirement = (17) 772 t The specific compl:essor inlet volume is:

r7 Specific Compressor Inlet Volume =(18) The number of equivalent effects is:

Equivalent Effects - m'AH 09) Qt, Table 1 shows the expected energy efficiency of a desalination system driven by a high-efficiency engine (vt - 0.6), such as a combined cycle (e.g., i3rayton + Rartkine) or a high-efficiency regenerated Brayton cycle. Table 2 shows the expected energy efficiency of a desalination system driven by a medium-efficiency engine (vl - 0.4), such as a large Diesel engine. The AT across each evaporator heat exchanger is assumed to be 6°C. Table 3 shows relevant properties of water.

]'able 1. Properties of combined cycle vapor-compresslon evaporator (Basis = i kg through compressor) 25 I 1_>6 i 2'1°° 1 T PI n, Tz P 2 Comp. x m,, m ] ±n m, IWm, Q,im, Ythnr Equiv.

(°C) (at-m) (OC) (atrn) Ratio (kg) (kg)} (kg) (kg) (kJikg) (kl/kg) (rn3/kg) Effects Fable 2. Properties of Diesel cycle val or-compression evaporator (Basis = 1 kg through compressor) 6 04 0.6 12.1°° I TI PI lru T 2 .P Camp. x m,. m,, m me l ;r¥/ nr Q 1 /mt F1fml Equiv.

(°C) (ahn)(OC) (arm) Ratio(kg) (kg) (kg) .(kg) ](ldlkg)'(kJlkg) (m3/kg) Effects F ] o0 1 .oo 5 130' 2.66 2.66 0.084!_ , 5.42 1.01 1.33 7.76 38.34 95.90 0.21 21.90 160 6.10 6,10 0,164 11.65 1.97 2.60 16.21 35.93 89.82 O,tO 23.38 .... iJ , 148 4.45 5 1781 9.44 2.12 0,077 5.39 1.461 i.i0 7,95 31.11 77,77 0.051 27.00 208 18.07 4.06 0.154 11.54 2.91 2.I6 16.60 29.09 72.71 0.025 28.88 _J 178 9.44 5 208 lg.07 1.91 0,076 5,38 1.74 0.98 8.10 27.20 67.99 0.024 30 89 238 31.87 3.391 0.154 [1.54 3.52 1.92 t6.98 25.28 63.20 0.012 33.23 220 22.87 5 250 39.22 1,71 0.08 5.40 2.21 0.83 8.44 22.07 55.17 0.0i 38.06 t0 280 63.29 2.77 0.169 11.69 4.65 1.61 17.95 20.13 5o3 o oo4 4, 2 256 43.35 5 286 69.22 1.60 0.093 5.46 2.84 0.71 9.02 ]7.67 44.16 0.0048 47.5.5 J Table 3. Thermodynamics of saturated water at G°C temperature intervals.

P T V H s atrn C m3/kg king kJ/kg-K Liquid.999998 100.000 .10434E-2 418.371 1.30434 Vapor.999998 100,000 1.67359 2674.95 7.35172 Liquid 1.23396 106.000 .10482E-2 443.704 1,37163 Vapor 1.23396 106.000 1.37482 2684.34 7.28125 Liquid 1.51134 112.000 .I0533E-2 469.090 1.43798 Vapor 1.51134 112.000 1.1 3728 2693.51 721344 Liquid 1.83798 118.000 .10585 E-2 494.534 1.50344 Vapor t,83798 118.000 .946974 2702,44 7.14809 Liquid 2.22025 124.000 .10640E 2 520.041 1.56805 Vapor 2.22025 124.000 .793416 2711,11 7.085O5 Liquid 2.66494 130.000 .10697E-2 545.617 1.631 Vapor 2.66494 130.000 .668659 2719.52 7,02414 Liquid 3.17935 136.000 ,10756E-2 571.270 1.69487 Vapor 3.17935 136.000 .566639 2727.63 6.96522 Liquid 3.77124 I42.000 .10818E-2 597.006 1.75716 Vapor 3,77124 142.000 .482696 2735.43 6.90814 Liquid 4.44882 148,000 .10883E-2 622.831 1.8!874 Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid ra_3fkg Vapor 123.619 328,000 .13453E-I 2672.68 5.45889 Liquid 133.521 334.000 .15888E-2 1551.84 3,59146 Vapor 133.521 334.000 ,12070E-1 2648.67 5,39798 Liquid 144.043 340.000 ,16374K-2 1593.86 3.65750 Vapor 144.043 340.000 .10783E-1 2620,76 5.33230 Liquid 155.221 346.000 .1695I E-2 1638.59 3.72704 Vapor I55.221 346.000 .95772K-2 2587.97 5.26040 Liquid 167,097 352.000 .17657E-2 1687.02 3,80153 Vapor 167.097 352.000 .84336K-2 2548.74 5.17996 Liquid 179.723 358.000 .18569E-2 1740.90 3.88361 Vapor 179.723 358.000 .73286E-2 2500.29 5,08679 Liquid • 193,166 364.000 .19856E-2 1804.09 3,97913 Vapor 193.166 364.000 .62194E-2 2436.52 4,97172 Liquid 207,538 370,000 .22134E-2 1889,64 4.10798 Vapor 207.538 370.000 .49783E-2 2337.17 4.80382 Liquid 217.755 373.990 .31056E-2 2087.96 4.41107 Vapor 217.755 373.990 .31056E-2 2087.96 4.41107 In both Tables 1 and 2, the energy efficiency improves at higher T 1 . This may be explained as follows:

a. At higher temperatures Tj, to achieve a given temperature difference across the vapor-compression evaporators, the compression ratio reduces. This factor reflects the underlying thermodynamics of water.

b. At higher temperatures T 1 . it is possible 1o have more stages in the multieffect evaporator.

Another benefit of operating at higher temperatures is that the pressure increases as well, which raises the density of the vapors entering the compressor. This allows the compressor to t>e smaller, and more economical, The compressor size may be farther reduced by increasJ_ag the number of stages in the vapor-compression evaporator section.

Yet another benefit of operating at higher temperatures is the compression ratio reduces, which allows the use of straight-Iobe compressors, which are only ertergy efficient at low compression ratios. Straight-lobe compressors are particularly desirable because they are inexpensive compared to other compressor types. Also, their speed and performance characteristics are well matched to Diesel engines, which are energy-efficient and low-cost.

Normally, desalination kent exchangers are limited to about I20"C. Above this temperature, calcium and magnesium carbonates and sulfates precipitate and may foul heat exchanger surfaces. This temperature may be too low to lly realize the benefits of hightempelature vapor-compression evaporation.

In some embodiments, non-stick coatings may prevent fouling of heat exchanger surfaces. There are many coating possibilities. A few are listed below, but others are contemplated by the present invention:

a Teflon coating onto metal. Dupont Silverstone Teflon coatings used for cookware may sustain temperatures of 290°C.

b. Aluminmn may be hard anodized followed by PTFE (poiytetrafluoroethyl one) inclusion.

c. Vacuum alaminization of cmbon steel, followed by hard anodizing and PTFE inclusion.

d. Impact coating of aluminum, carbon steel, or naval brass with PPS (polyphenylene sulfide) or PPS/PTFE alloy.

Such coatings maybe applied to the side of the heat exchanger that is exposed to the hot saltwater. In one embodiment, the base metal would ineNde a saltwater-resistant material, such as naval or admiralty brass. Using this approach, should the coating fail, the heat exchanger may foal but it would not perforate or leak.

At Iower temperatures (-- 120°C), the non-stick surfaces may not be necessary; however, saltwater resistance may be imparted by cathodic-are vapor deposition of titanium on other metals, such as aluminum or ca-bon steel. As an alternative to coating the metal surface, it may be possible to bond a thin polymer film, such as PVDF (polyvinylidenedifluoride) or PTFE; using suitable adhesives and/or heat lamination.

In some embodiments where precipitates stick to the coated or fihned surfaces, it may be possible to add inert solid particulates to the circulating salt solution that continuity scour and eIean the fouled surfaces. Prior to discharging the salt solution, these inert solid particulates would be recovered artd recycled to the incoming salt solution.

Alternatively, or additionally, the heat exchanger could be taken out of service temporarily to clean the surfaces with dilute acids or other appropriate cleaners.

The condensing side of the heat exchanger is less demanding. If the base metal resists steam (e.g., naval brass), no additional coatings are needed. However, if a less resistant metal is used, such as carbon steel or aluminum, it may be desirable to treat the eoJadensiag surface as follows:

a. Hot-dip galvanizhag of carbon steel.

b. Conversion anodizing of aluminmn.

13. Vacuum aluminizing of carbon steel, followed by anodizing.

d. Electroless coating of nickel on aluminum or carbon steel.

e. Electroplating of cadmium, nickel, or zinc on aluminum or carbon steel, f. Dip/spray/roller coating of almninmn or carbon steel with PVDF paint.

All of the above coatings or films, for both the saltwater side and steam side, may be applied by "coil coating." In this method, a large roll ofsheet metal is continuously unwound and treated to apply the coating or fiIm. The final product is agaht rolled into a coil and shipped. This method is well known as m economical method for applying highquality coatings to raetal surfaces.

FIGURES 9 through 48 illustrate Various embodiments of heat exchanger assemblies accordiiag to various embodiments of the present invention.

FIGURE 9 illustrates an example indented sheet 300a of a sheet assembly for use in a heat exchanger assembly m accordance with one embodiment of the invention. Indented sheet 300a may be used in any suitable heat exchanger, such as say of the embodhnents of heat ex13hanger assembly 500 shown in FIGURES 27-48 discussed below and/or heat exchanger assembIy 500 shown in FIGURES 56-57 of U.S. Patent Application Serial Number 10/944,374 referenced above, for example.

Indented sheet 300a includes a plurality of dimples 304 formed h-L an indentation pattern 302. Indentation pattern 302 includes an indentation pattern section 303 repeated multiple times on sheet 300a. In the embodiment shown ka FIGURE 9, indentation pattern section 303 includes a row of dimples 304. To form indented sheet 300a, indentation pattern section 303 may be stamped into a blank sheet at multiple locations on the sheet 300a. For example, to create indented sheet 300a shown in FIGURE 9, the indentation pattern section (i.e., row) 303 may be stamped into a blank sheet at one position, the sheet may be advanced or indexed, the indentation pattern section (i.e., row) 303 may be stamped into the new location, and so oft to form the complete array of dimples 304. Using such process allows for a relatively small metal stamp to be used to create the dimples 304, which may save expenses.

FIGURE 10 illustrates an example metal stamping pro13ess for forming indented sheet 300a in accordance with one embodiment of the invention. A metal stamping assembly 310 includes a male die 3 I2 having one or more protrusions 314 and a female die 316 having one or more openings 318 configured to receive protrusions 314. At step (a), a blank metal sheet 320 is positioned between male die 3!2 and female die 316. At step Co), male die 312 and female die 316 come together, causing protrusions 314 to form dimples 304 in blank sheet 320. At ste p (c), male die 312 and female die 316 are moved apart, allowing the metal sheet to be repositioned between male die 312 and female die 316. This process may be repeated Jn order to form the complete array of dimples 304 in indented sheet 300a.

FIGURE l t illustrates an example hydroforming process for forming indented sheet 300a in accordance with one embodiment of the invention. A hydroforming assembly 330 includes a male die 332 configured to house a fluid 334 and a female die 336 having one or more openings 338 configured to receive fluid 334. At step (a), a blank metal sheet 320 is positioned between male die 332 and female die 336. At step (b), male die 332 and female die 336 come together and high-pressure fluid 334 is directed into male die 332, causing portions of blank sheet 320 to deform into openings 338 in female die 336, thus fom-dng dknples 304 hi blank sheet 320. At step (c), male die 332 and female die 336 are moved apart, allowing the metal sheet to be repositioJaed between male die 332 and female die 336.

This process may be repeated m order to form the complete array of dimples 304 in indented sheet 300a.

F OURE 12 illustrates an example indented sheet 300b of a sheet assembly for use in a heat exchanger assembly in accordance with another embodiment of the invention.

Indented sheet 300b includes a first pInrality of indented ridges 340 extending along a first direction 342 and a second plurality of indented ridges 344 extending along a secorld direction 346 generally perpendicular to first direction 342. FIGURE 12 also shows crosssectional views of indented sheet 300b taken along lines A-A and B-B. Indented ridges 340 and 344 prevent (or at least reduce the likelihood of) sheet 300b for warping, thus increasing the durability of sheet 300b and providing easier handling of sheet 300b.

FIGURE 13 illustrates an example roller assembly 350 for forming ridges in a metal sheet 320, such as ridges 340 or 344 in indented sheet 300b, for example, in accordance with another embodiment of the invention. Roller assembly 350 includes a male roller 352 and a female roller 354. A blank metal sheet 320 may be positioned between male roller 352 and femaIe roller 354, and one or both of male roller 352 and female roller 354 may rotate, as indicated by arrows 356 and 358, after (or while) being moved toward each other in order to form a series of ridges in the metal sheet 320, such as fi 1 e series of ridges 340 in indented sheet 3 00b, for example.

FIGURE t4 illustrates a cross-section of sheet assembly 360 including spacers 362 positioned between adjacellt sheets 364 in a heat exchanger assembly in accordance with another embodiment of the invention. Such configuration may be used in any suitable heat exchanger assembly, such as any of the embodiments of heat exchanger assembly 500 shown in FIGURES 27-48 discussed below and/or heat exchanger assembly 500 shown in FIGURES 56-57 of U.S. Patent Application Serial Number t0/944,374 referenced above, for example.

Sheet assembly 360 includes a plurality of sheets 364 positioned generally parallel to each other, and may define a plurality of relatively low-pressure passageways 366 extending in a first direction alternating with a plurality of relatively high-pressure passageways 36g extending in a second direction perpendicular to the first direction, such as described above with reference to first and second passageways 582 and 586 shown in FIGURE 57A of U.S. Patent Application Serial Number 10/944,374 referenced above, for example. In this example embodiment, high-pressure passageways 368 extend in a first direction indicated generally by arrows 370, and low-pressure passageways 366 extend in a second direction generally into/out of the page. Sheets 364 may include indentations (such as dhnples, ridges or other protrusions) 366, such as discussed above. Indentations 366 may contact each other in the low-pressure passageways 366, thereby ensuring that low-pressure passageways 366 remain open when high pressures are applied within high-pressure passageways 368.

Spacers 362 are positioned between adjacent sheets 364 and operate to provide desired spacing between sheets 364. In some embodiments, spacers 362 include grooves 371 that are filled with a sealer 372, which may include any suitable material and/or device suitable for providing a fluid seal. For example, sealer 372 may comprise an elastic O-ring or other appropriate gasket material. In this embodiment, spacers 362 have an I-beam cross-section. However, other suitable cross-sections may be used. Spacers 362 may be formed in any suitable manner, such as using extrusion techniques, for example. Some spacers 362 may be solid, whereas others may include holes or openings 376 allowing fluid to flow through. For example, in the particular cross-section shown in FIGURE 13, spacers 362a located between adjacent sheets 364 that define a low-pressure passageway 366 may be solid, because e fired flows in the directiort into/out of tl e page, whereas spacers 362?o located between adjacent sheets 364 that define a l gh-pressure passageway 368 may igclude openings 376, allowing fluid to flow through such passageways 368 generally in the first direction 370.

FIGURE t4 also illustrates side views of spacers 362a and spacers 362b, w ch are shown above the illustration of sheet assembly 360. As discussed above, spacers 362a may be solid, whereas spacers 362b may include openings 376 allowing fluids to pass through.

Such openings 376 may be formed after the relevant spacer 362b is formed (e.g., by extrusion).

FIGURES 15 and !6 illust 1 :ate a configuration of a spacer 362a according to one embodiment of the invention. FIGURE 15 illustrates a top view of spacer 362a. Spacer 362a forms a generally rectangntar ring inchding four length members 380a and four comer members 382a. FIGURE 16 illustrates an exploded perspective view of a comer region of spacer 362a shown in FIGURE 15. In particular, FIGURE 16 shows a comer member 382a, and a first length member 380a and a second length member 380a' which connect to comer member 382a. First length member 380a includes openillgs 376a, whereas second length member 380a' is solid. Such configuration may be used to provide fluid flow ir the direction indicated generally by arrow 386a. Comer member 382a includes a groove 388a, which may align with grooves 371a and 37ta' formed in length members 380a mad 380a' such that grooves 388a, 371a and 371a' may cooperate to accept a gasket or other sealer 372.

FIGURES 17 and 18 illustrate a configuration of a spacer 362b according to another embodiment of the invention. FIGURE 17 illustrates a top view of spacer 362b. Spacer 362b forms a generally rectangular ring including four length members 380b. FIGURE 18 illustrates an exploded perspective view of a comer region of spacer 362b shown ia FIGURE 17. In particular, FIGURE 18 shows how two length members 380b meet to form a comer. Each length member 380b may be cat at 45 degrees, thus providing a 90-degree comer between adjacent length members 380b. First length member 380b includes openings 376-b, whereas second length member 380b' is solid. Again, such configuration may be used to provide fluid flow in the di_veetiort indicated generally by arrow 386-b.

Grooves 371b and 371b' formed in length members 380b and 380b' may align at the comer and cooperate to accept a gasket or other sealer 372.

FIGURES 19 and 20 illustrate a configuration of a spacer 362c according to another embodiment of the invention. FIGURE 19 illustrates a top view of spacer 362c. Spacer 362c forms a genexaUy rectangular ring including four length members 380c and four comer member 382c. Each length members 380c and each corner member 382c may be cut at an angle at each end such that length members 380c corner member 382c join to fore 1 90-degree corners. Pot example, each end of each length members 380c and each comer member 382c may be cut at a 22.5 degree angle in order to form 90-degree comers.

FIGURE 20 illustrates an exploded perspective view of a comer region of spacer 362c shown in FIGURE 19, In particular, FIGURE 20 shows a comer member 382c, and a first length member 380c and a second length member 380c' which connect to comer member 382c. First length member 380c includes openings 376c, whereas second length member 380c' is solid. Such configuration may be used to provide fluid flow in the direction indicated generally by arrow 386c. Comer member 382c includes a groove 388c, which may align with grooves 371c aad 371c' formed in length members 380c and 380c' such that grooves 388c, 371c and 371c' may cooperate to accept a gasket or other sealer 3"72.

FIGURES 21 and 22 illustrate a configuration of a spacer 362d according to another embodiment of the invention. FIGURE 21 illustrates a top view of spacer 362d. Spacer 362d forms a generally rectangular ring including four length members 380d and four comer members 382d. Each length members 380d and each comer member 382d may be cllt at an angle at each end such that length members 380d comer member 382d join to form 90-degree comers. For example, each end of each length members 380d and each comer member 382d may be cut at a 22.5 degree angle in order to form 90-degree comers.

FIGURE 22 illustrates an exploded perspective view of a comer region of spacer 362d shown in FIOURE 21. In particular, I IGLYRE 22 shows a comer member 382d, and a first length member 380d and a second length member 380d' which connect to comer member 382d. First Length member 380d includes openings 376d, whereas second length member 380d' s solid. Such cordiguration may be used to provide find flow in the direction indicated generally by arrow 386d. Comer member 382d includes a groove 388d, which may align with grooves 371d and 371d' formed in length members 380d and 380d' such that grooves 388d, 371d and 371d" may cooperate to accept a gasket or other sealer 372.

Like groove 388a shown in FIGURE 15, groove 388d is curved, which may be adva tageons for accepting a sealer 372, such as an O-ring or other gasket, for example.

FIGURE 23 illustrates a perspective view of an ortho-grid sheet assembly 400a including a plurality of sheets 402a in accordance with one embodiment of the invention.

Sheet assembly 400a may be used in any suitable heat exchanger assembly, such as any of the embodiments of heat exchanger assembly 500 shown m FIGURES 27-48 discussed below and/or heat exchanger assembly 500 shown in FIGURES 56-57 of U.S. Patent Application Serial Number !0/944,374 referenced above;for example.

Sheet :assembly 400a includes, a plurality of sheets 402a positioned generally parallel to each other, and may define a plurality of relatively low-pressure passageways 404a extending in a first direction, alternating with a plurality of relatively high-pressure passageways 406a extending in a second direefion perpendicular to the first direction. In this example embodiment, tow-pressure passageways 404a extend in a first direction indicated generally by arrow 408a, and high-pressure passageways 406a extend in a second direction indicated generally by arrow 410a. Rectangular (e.g., square) tubing 416a is located between, and coupled to, sheets 402a such that passageways 404a mid 40ha are maintained between sheets 402a. Rectangular tubing 416a may be formed from metal or other suitable material and may be rigidly bonded to sheets 402a by any suitable means, such as by adhesive, braze or weld, for example.

FIGURE 24 illustrates an exploded view of a portion of the o aho-grid sheet assembly 4O0a of FIGURE 23. In this embodiment, rectangular tubing 416a is bonded to one side of each sheet 402a of assembly 400a.

FIGURE 25 illustrates a perspective view of an ortho-grid sheet assembly 400b including a plurality of sheets 402b in accordance with another embodiment of the invention. Sheet assembly 400b maybe sed in any suitable heat exchanger assembly, snch as any of the embodfinents of heat exchanger assembly 500 shown in FIGURES 27-48 discussed below and/or heat exchanger assembly 500 shown in FIGURES 56-57 of U.S.

Patent Application Serial Number 10/944,374 referenced above, for example.

Sheet assembly 400b includes a plurality of sheets 4021o positioned generally paralteI fo each other, and may define a plurality of relatively low-pressure passageways 404b extending in a first direction, alternating with a plurality of relatively high-pressure passageways 406b extending in a second direction perpendicular to the first direction, such as described above with reference to first and second passageways 404a and 406a, ibr example. In this example embodiment, low-pressure passageways 404b extend in a first direction indicated generally by arrow 408b, and high-pressure passageways 406b extend in a second direction indicated generally by arrow 410b. Rectangular (e.g., square) tubing 416b is located between, and coupled to, sheets 402b such that passageways 404b and 406b ace maintained between sheets 402b. Rectangular tubing 416-b may be formed from metal or other suitable material and may be rigidly bonded to sheets 402b by any suitable means, such as by adhesive, braze or weld, for example. In this embodiment, rectangular tubing 416b is rigidly bonded to the lowLpressure side of the relevant sheet 4025. This may provide of maintaining the bond between the rectangular tubing 416b and the sheet 402b in compression (and not in tension). Using such approach, a failme of the bond may not lead to a failure of the heat exchanger.

FIGURE 26 illustrates an exploded view of a portion of the ortho-grid sheet assembly 400b of FIGURE 25. As discussed above, h this embodiment, rectangular tubing 416b is rigidly bonded to the low-pressure side of each sheet 402a of assembly 400a.

FIGURE 27 illustrates a cross-section of an example heat exchanger assembly 500 including a shell 510 and a sheet assembly 512 disposed within shell 510 in accordance with an embodiment of the invention. Shell 510 may comprise any suitable shape and may be formed from any suitable material for housing pressurized gasses and/or liquids. For example, in the embodiment shown in FIGURE 27, shell 510 comprises a substantially cylindrical portion 516 and a pair of hemispherical caps 600 (see FIGURE 28) coupled to each end of cylindrical portion 516. The cross-section shown in FIGURE 27 is taken at a particular point along the length of cylindrical portion 516, which length extends in a direction perpendicular to the page.

In general, heat exchanger assembly 500 is configured to allow at least two fluids (e.g., a relatively low-pressm'e fluid and a relatively high-pressure fluid) to be communicated into shell 510, through passageways defined by the plurality of sheets 513 forming sheet assembly 512 (such as relatively low-pressure passageways and relatively high-pressure passageways discussed above with regard to various embodiments) such that heat is lrm sferred between the fluids, and ol_at of shell 510, Shell 510 may incIude any number of inlets and outlets for communicating fluids into and out of shell 5 !0. In the embodiment shown in FIGURE 27, shell 510 includes a first inlet 520, a first outlet 522, a second inlet 524, a secoi d outlet 526 and a third outlet 528. First inlet 520 and first outlet 522 are configured to communicate a first fluid (e.g., a relatively high-pressure fluid) 530 into and out of shell 510. Second inlet 524, second outlet 526, and third outlet 528 are configured to communicate a second fluid (e.g., a relatively low-pressure fluid) 552 into and out of shall 510.

Due to the transfer of heat between first fluid 550 and second fluid 532, at least a portion of first fluid 530 and/or second fluid 532 may change state within shell 510 and thus exit shell 510 in a different state than such fluids 530 and/or 532 entered shell 510. For example, in a particular embodiment, relatively high-pressure steam 534 enters shelt 510 through first inlet 520, enters one or more first passageways within sheet assembly 512, becomes cooled by a liquid 540 flowing through one or more second passageways adjacent to the one or more first passageways within sheet assembly 512, which causes at least a portion of the steam 534 to condense to form steam condensate 536. The steam condensate 536 flows toward and through first outlet 522. Concurrently, liquid 540 (saltwater, seawater, concentrated fermentation broth, or concentrated brine, for example) ei 1 ters shell 510 throuOl second inlet 524, osiers one or more second passageways within sheet assembly 512, becomes heated by steam 534 flowing through the one or more first passageways adjacent to the one or more second passageways within sheet assembly 512, which causes at least a portion of the liquid 540 to boil fo form relatively low-pressure steam 542. The low-pressure steam 542 escapes from shell 510 through second outlet 526, whereas the unboiled remainder of liquid 540 flows toward and through third outlet 528.

In some embodiments, heat exchanger assembly 500 includes one o, more pumps 550 operable to pump liquid 540 that has exited shell 510 through third outlet 528 back into shell 510 through second inlet 524, as indicated by arrows 552. Pump 550 may comprise any suitable device or devices for pumping a fluid through one or more fluid passageways.

As showtl in FIGURE 27, liquid 540 may be supplied to the circuit through a feed input 554. In embodiments in which liquid 540 comprises a solution (such as a seawater solution, for example), a relatively dilute form of such solution (as compared with the solution exiting shell 510 through third output 528) may be supplied through feed input 554. In addition, a portion of liquid 540 being pm-nped toward second inlet 524 of shell 510 maybe redirected away from shell 510, as indicated by arrow 556. In embodiments in which liquid 540 comprises a solution (such as a seawater solution, for example), such redirected liquid 540 may comprise a relatively concentrated foma of such solution (as compared with the diluted solution supplied through feed input 554). Although inlets 520, 524 and outlets 522, 526 and 528 are described herein as single inlets and outlets, each inlet 520 7 524 and each outlet 522, 526 and 528 may actually include any suitable number of inlets or outlets.

In some embodiments, first fluid 530 generally comprises vapor and second fluid 532 generally comprises a liquid, as least when first fluid 530 and second fluid 532 enter shell 510 through inlets 520 and 524, respectively. In particuIar embodiments, second fluid 532 may comprise saltwater, seawater, fermentation broth, or brine.

Heat exchanger assembly 500 may also include a plurality of mounting devices (or tracks) 560 coupled to shell 510 and operable to mount sheet assembly 512 within shell 510.

Each mounting device 560 may be associated with a particMar comer of sheet assembly 512. Each mounting device 560 may be coupled to shell 510 in any suitable mariner, such as by welding or using fasteners, for example. In the ernbodiment shown in FIGURE 27, each mounting device 560 comprises a 90-degree Y-shaped bracket into which a comer of sheet assembly 512 is mounted. Each mounting device 560 may extend along the length of shell 510, or at least along the length of a portion of shell 510 in which fluids 530 and 532 are coIranuaicated, in order to create two volumes within shell 510 that are separated from each other. A first volume 564, which includes first and second chambers 580 and 582 generally to the left and fight of sheet assembly 510, as well as one or more first passageways defined by sheet assembly 510, is used to communicate first fluid 530 through heat exchanger assembly 500. A second volume 566, which includes third and fourth chambers 584 and 586 generally above and below sheet assembly 510, as well as one or more second passageways defined by sheet assembly 510, is used to communicate second fluid 532 through heat exchanger assembly 500.

Because first volume 564 is separated from second volume 566 by the configuration of sheet assembly 512 and mounting devices 560, first fluid 530 is kept separate from second fluid 532 within shell 510. In addition, one or more gaskets 562 may be disposed between each Y-shaped bracket 560 and its corresponding comer of sheet assembly 512 to provide a seal between first volume 564 and second volume 566 at each comer of sheet assembly 512. Gaskets 562 may comprise any suitable type of seal or gasket, may have any suitable shape (such as having a square, rectangular or round cross-section, for example) and may be formed from any material suitable for forming a seal or gasket.

Heat exchanger assembly 500 may also include one or more devices for sliding, rolling, or otherwise positioning sheet assembly 512 within shell 510. Such devices may be particularly useful in embodiments in which sheet assembly 512 is relatively heavy or massive, such as where sheet assembty 512 is formed from metal. In the embodiment shown in FIGURE 27, heat exchanger assembly 500 includes wheels 568 coupled to sheet assembly 512 that may be used to roll sheet assembly 512 into shell. Wheels 568 may be aligned with, and roll on, wheel tracks 570 coupled to shell 510 in any suitable manner.

FIGURE 28 illustrates an example side view of heat exchanger assembly 500 shown i a FIGURE 27 in accordance with an embodiment of the havention. As shown in FIGURE 28, sheet assembly 512 is disposed within shell 510, which includes substantially cylindrical portion 516 and a pair of hemispherical caps 600 coupled to each end of cylindrical portion 516. Hemispherical caps 600 may include a flange portion 602 coupled to a flange portion 604 of cylindrical portion 516 by one or more coupling devices 606, such bolts, rivets or welds for example. Sheet assembly 512 may include a first e d plate 612 and a second end plate 614 welded or otherwise rigidly coupled to an inside surface of shell 510, such as indicated by arrows 610.

FIGURES 29 and 30 illustrate cross-sectioJaal views A, B, C, D, E d F taken along lines A-A, B-B, C-C, D-D, E-E and F-F respectively, shown ha FIGURE 28 in accordance with another embodiment of the invention. In this embodiment, motmting devices (or tracks) 560a used to hold sheet assembly 512a in position within shell 510 comprise 90degree Y-shaped brackets into which the comers of sheet assembly 512 a are mounted.

As shown in FIGURE 29, view A shows hemispherical cap 600, including flange portion 602. View B shows first end plate 6!2 and cylindrical portion 516 of shell 510, inctndhag flange portion 604. As discussed above, first end plate 612 is welded or othenvise rigidly coupled to an inside surface of shell 510, as indicated by arrows 610. First end plate 612 may include one or more holes 616 operable to allow pressure to equalize across the surfaces of sheets 513 of sheet assembly 512a. View C and D show baffles 620a and 622a !oeated in high-pressure chambers 582 and 580, respectively.

As shown in FIGURE 30, view E shows second end plate 614 and cylindrical portion 516 of shell 510, iaachlding flange portion 604. As discussed above, first cud plate 612 is welded or otherwise rigidly coupled to an inside surface of shell 510, as indicated by arrows 610. Like first end plate 612, second end plate 614 may include one or more holes 616 operable to a!Iow pressure to equalize across the surfaces of sheets 5!3 of sheet assembly 512a. A push plate 630a may be located at the center of second end plate 614.

Push plate 630a may compress the sealers 372 (e.g., O-rings or gaskets) located in spacers 362. Thus, push plate 630a may have a similar shape as the cross-sectional shape of sheets 513 (here, a square oI rectangle). The outer periphery of pusher plate 630a may be sealed to second end plate 6t4 using an O-ring or other suitable gasket.

Also shown in FIGURE 30, view F shows mounting devices (or tracks) 560a coupled to shell 510 and used to hold sheet assembly 512 a in position within shell 5 t 0. As discussed above, each mounting track 560a may be associated with a particular comer of sheet assembly 512a. Also, each mounting track 560a may be coupled to shell 510 in any suitable manner, such as by welding or using fasteners, for example. As discussed above, each mounting track 560a comprises a 90-degree Y-shaped bracket into wtfich a comer of sheet assembly 512a is mounted. Each mounting device 560a may extend along the length of cylindrical portion 516 of shell 510, or at least along a portion of the length of cylindrical portion 516. One or moire gaskets (or other suitable sealing device) 634a may be located adjacent each mounting track 560a in order to seal sheet assembty 512a to that mounting track 560a. h some embodiments, gaskets 634a may be hollow and inflated with pressurized liquid or gas to ensure a good seal. As shown in FIGURE 28, a hydraulic mechanism 638 may be used to compress the sheets 513 of sheet assembly 5t2a together.

Trapped gas in the elevated chamber 639 acts as a spring to allow sheet assembly 512a to flex during temperature changes.

FIGURES 31 d 32 illustrate cross-sectional views A, B, C, D, E and F taken along lines A-A, B-B, C-C, DmD, E-E and F-F respectively, shown in FIGURE 28 in accordance with another embodiment of the invention. In this embodiment, mounting devices (or tracks) 5601o used to hold sheet assembly 512b in position within shelI 510 comprise 45degree brackets into which the comers of sheet assembly 512b are mounted.

As shown in FIGURE 31, view A shows hemispherical cap 600, including flmage portion 602. View B shows first end plate 612 and cylindrical portion 516 ofshetl 510, including flange portion 604. As discussed above, first end plate 612 is wdded or otherwise rigidly coupled to art inside surface of shell 510, as indicated by arrows 610. First end plate 612 may include one or more holes 616 operable to allow pressure to equalize across the surfaces of sheets 513 of sheet assembly 512b. View C and D show baffles 6201o and 622b located in high-pressure chambers 582 and 580, respectively. As discussed above, mortaring tracks 560b comprise 45-degree brackets into which the comers of sheet assembly 512b are mounted. Thus, each comer of sheet assembly 512b may have a 45-degree angled portion, indicated as corners 640b.

As shown in FIGURE 32, view E shows second end plate 614 and cylindrical portion 516 of shell 510, incltuting flange portion 604. As discussed above, first end plate 612 is welded or otherwise rigidly coupled to an inside sin-face of shell 510, as indicated by arrows 610. Like first end plate 612, second end plate 614 may include one or more holes 616 operable to alloW pressure to equalize across the surfaces of sheets 513 of sheet assembly 512b. A push plate 630b may be located at the center of second end plate 614.

Push plate 630a may compress the sealers 372 (e.g., O-rings or gaskets) located in spacers 362. Thus, push plate 630b may have a similar shape as the cross-sectional shape of sheets 513 (here, a square or rectangle ha, Ang 45-degree angled comers). The outer periphery of pusher plate 630b may be sealed to second end plate 614 using an O-ring or other suitable gasket.

Also shown in FIGURE 32, view F shows mounting devices (or tracks) 560b coupled to shell 510 and used to hold sheet assembly 512b in position within shell 510, As discussed above, each mounting track 560b may be associated with a particular comer of sheet assembly 512b. Also, each mounting track 560b may be coupled to shell 510 in any suitable maturer, such as 5y welding or using fasteners, for example. Each mounting device 560b may extell.d along the length of cylindrical portion 5!6 of shell 510, or at least along a pofdon of the length of cylindrical portion 516. One or more gaskets (or other suitable sealing device) 634b may be located adjacent each mounting track 560b in order to seal sheet assembly 512b to that mounting track 560b. In some embodiments, gaskets 634b may be hollow and inflated with. pressurized liquid or gas to ensure a good seal. As shown in FIGURE 28, a hydraulic mechanism 638 may be used to compress the sheets 513 of sheet assembly 5125 together. Trapped gas in the elevated chamber 639 acts as a spring to allow sheet assembly 512b to flex during temperature changes.

FIGURES 33 and 34 illustrate cross-sectional views A, B, C, D, E and F taken along lines A-A, B B, C-C, D-D, E-E and F-F respectively, shown in FIGURE 28 in accordance with yet another embodiment of the invention. In this embodiment, mounting devices (or tracks) 560c used to hold sheet assembly 512c in position within shell 510 comprise rounded brackets into which the rounded comers of sheet assemb]y 512e ae mounted.

As shown in FIGURE 33, view A shows hemispherical cap 600, including flange portion 602. View B shows first end plate 612 and cylindrical portion 516 of shell 510, including flange portion 604. As discussed above, frost end plate 612 is welded or otherwise rigidly coupled to an inside surface of shell 510, as indicated by arrows 610. First end plate 612 may include one or more holes 616 operable to allow pressure to equalize across the surfaces of sheets 513 of sheet assembly 512c. View C and D show baffles 620c and 622c located in high-pressure chambers 582 and 580, respectively_ As discussed above, mounting tracks 560c comprise rounded brackets into which the comers of sheet assembly 512c are mounted. Thus, each corner of sheet assembly 512c may have a rounded comer portion, indicated as rounded comers 640c.

As shown in FIGURE 34, view E shows second end plate 614 and cylindrical portion 516 of sheet 510, including flange portion 604. As discussed above, first end plate 612 is welded or otherwise rigidly coupled to an inside surface of shell 510, as indicated by arrows 6t0. Like first end plate 612, second end plate 614 may include one or more holes 616 operable to allow pressure to equalize across the surfaces of sheets 513 of sheet assembly 512c. A push plate 630c may be located at the center of second end plate 614.

Push plate 630c may compress the sealers 372 (e,g., O-rings or gaskets) located in spacers 362. Thus, push plate 630c may have a similar shape as the cross-sectional shape of sheets 513 (here, a square or rectangle having rounded comers). The outer periphery of pusher plate 630c may be sealed to second end plate 614 wing art O-ring or other suitable gasket.

ALso shown in FIGURE 34, view F shows mounting devices (or tracks) 560c coupled to shell 510 and used to hold sheet assembly 512c in position within shetl 510. As discussed above, each mmmting track 560c may be associated with a particular comer of sheet assembly 512c. Also, each mounting track 560e may be coupled to shell 510 in any suitable manner, such as by welding or using fasteners, for example. Each mounting device 560o may extend along the length of cylindrical portion 516 of shell 510, or at least along a portion of the length of cyli_Mrieal portion 516. One or more gaskets (or other suitable sealing device) 634o may be located adjacent each mounting gack 560e in order to seal sheet assembly 512c to that mounting track 560e. In some embodiments, gaskets 634c may be hollow and inflated with presmzrized liquid or gas to ensure a good seal. As shown in FIGURE 28, a hydraulic mechanism 638 may be used to compress the sheets 513 of sheet assembly 512c together. Trapped gas in the elevated chamber 639 acts as a spring to allow sheet assembly 512c to flex during temperature changes.

I;IOURE 35 illustrates an example side view of heat exchanger assembly 500 shown in FIGURE 27 in aceordarme with atlother embodiment of the invention. The embodiment shown in FIGURE 35 is similar to the embodiment shown in FIGURE 35, except that a screw mechanism 650, rather than a hydraulic mechanism 638, is used to compress the sheets 513 of sheet assembly 512 together.

FIGURE 36 illustrates a perspective view of sheet assembly 512 having a first end plate, or baffle, 612a and a secortd end plate, or baffle 614a in accordance with one embodiment of the invention. End plates 612a and 614a may operate to seal tow-pressure chambers 580 and 582 f om high-pressure chambers 584 and 586.

FIGURE 37 illustrates a Top View and a Side View of a heat exchanger assembly 500 used Co transfer latent heat in accordance with one embodiment of the invention. Heat exchanger assembly 500 includes a plurality of sheets 513 defining a plurality of highpressure passageways 660 alternating with a plurality of low-pressure passageways 662.

The Top View illustrates the flow of a relatively high-pressure fluid through high-pressure passageways 660, as indicated by arrows 664. The Side View illustrates the flow of a relatively low-pressure fluid 666 through low-pressure passageways 662. As shown in the Top View, a number of baffles 668 are positioned within high-pressure chambers 580 and 582 at various locations along the length of assembly 500. Baffles 668 may be coupled to the inside surface of shell 5t0 and!or to the outer edges of sheet assembly 512 in order to block, and thus redirect, the flow of high-pressure fluids flowing through high-pressure passageways 660. As shown in the Top View, the high-pressure flow area progressively decreases as the high-pressure fluid moves from art inlet 670 to an outlet 672. This allows for the velocity of the fluid through the heat exchanger passageways 662 to remain relatively constant and pushes any non-compensable gases out through outlet 672. In the case of small heat exchanger assembly 500 that may have only a few heat exchanger sheets 513, the retatively constant velocity through the heat exchanger passageways 662 ea be achieved using spacers or varying width, in particular using relatively wide spacers near the inlet and relatively narrow spacers near the outlet. In this case, the vapor velocity through each passageway may be relatively constant.

FIGURE 38 illustrates a Top View and a Side View of a heat exchanger assembly 500 used to transfer sensible heat in accordance with another embodiment of the invention.

tteat exchanger assembly 500 includes a plurality of sheets 513 defining a plurality ofhighpxessure passageways 660 alternating with a plmality of low-pressure passageways 662.

Ti 1 e Top View illust, ates the flow of a first fluid through first passageways 660, as indicated by arrows 664. The Side View illustrates the flow of a second fluid through second passageways 662, as indicated by arrows 665. As shown in the Top View, a number of baffles 668 are positioned within chambers 580 and 582 at various locations along the length of assembly 500. As shown in the Side View, a number of baffles 668 are positioned within chambers 584 and 586 at various locations along the length of assembly 500. N this embodiment, baffles 688 are spaced equally, which allows for a constant velocity through the heat exchanger passageways 660 and 662.

FIGURE 39 illustrates a Top View and a Side View of a heat exchanger assembly 500 used to transfer both latent heat and sensibte heat within a single shell 510 hn accordance with another embodiment of the invention. Thus, heat exchanger assembly 500 shown in FIGURE 39 may be essentially a C 01 nbJ_n.ation of the heat exchanger assemblies 500 shown in FIGURES 37 and 38. Iin this embodiment, heat exchanger assembly 500 includes a first portion 700 configured *o transfer sensible beat, a second portion 702 configured to transfer latent heat, and a third portion 704 configured to transfer sensible heat. First and third portions 700 and 704 may have similar configurations as that shower in FIGURE 38 and discussed above. Second portion 702 may have a similar conIignratio-n as that shown in FIGURE 37 and discussed above.

FIGURES 40 and 41 illustrate a heat exchanger assembly 500 having thermosiphoning in accordance with another embodiment of the invention. As shown in FIGURES 40 and 41, heat exchanger assembly 500 includes a first end plate 612 and a second end plate 614 at opposite ends of sheet assembly 5!2. End plates 612 and 614 include baffles 668 on each side of sheet assembly 512 that prohibit high-pressure fluid, indicated by arrows 710, from flowing beyond the ends of sheet assembly 512. However, end plates 6!2 and 614 do not have restrictive baffles on the fop or bottom of sheet assembly 512, thus allowing low-pressure fluid 712 to flow beyond_, and around, the ends of sheet assembly 512, as indicated by arrows 714.

FIGURE 42 illustrates a cross-section of an example heat exchanger assembly 500 including a shell 5t0 and a sheet assembly 5t2 disposed within shell 510 in accordance with another embodiment of the invention. This embodiment may be similar to that shown in FIGURES 27-28 and discussed above. However, tbis eml odiment may be desirable for assembling sheet assembly 512 outside of shell 510 and inserting and mounthlg sheet assembly 512 inside shell 510.

Because sheet assembly 512 may be relatively large and!or heavy, sheet assembly 512 may be guided into shell 510 by o11e or more insertion mechanisms 730 for sliding, rolling, or Otherwise positioning sheet assembly 512 within shell 510. In the embodiment shown i 11 FIGURE 42, such insertion mechanisms 730 include a number of milers 732 located within tracks 734. The assembled sheet assembly 512 may be roiled into cylindrical portion 516 of shell 510 using brackets 560 located at mid/or rigidly coupled to each comer of sheet assembly 512. Additional guiding members 740 may be coupled to shell 510 in order to guide or align the insertion of sheet assembly 512 into shell 510. A sealant 738, such as silicone or tar, for example, may be inserted (a) between brackets 560 and each comer of sheet assembly 512 mldYor Co) between brackets 560 and portions of insertion mechanisms 730 and/or other guiding members 740 associated with shell 510. Sealant 738 may eliminate or reduce leakage between high-pressure chambers 580, 582 and lowpressure chambers 584, 586.

FIGURE 43 illustrates a cross-section of an example heat exchanger assembly 500 including a shell 510 and fi sheet assembly 512 disposed within shell 510 in accordance with yet another embodiment of the invention. This embodiment may be similar to the embodiment shown in FIGURE 42 and discussed above, except using inflatable gaskets 744 instead of sealant 738 between brackets 560 and portions of insertion mechanisms 730 and/or other guiding members 740 associated with shell 510. Inflatable gaskets 744 may be hollow gaskets filled with high-pressure gas or liquid, and may be constructed of elastomeric materials or malleable metal, for example. In this embodiment, sealant 738 may still be 11sed to provide a seal between brackets 560 and each comer of sheet assembly 512.

FIGURE 44 illustrates a perspective view of an assembled sheet assembly 512 for insertion into shell 510 in accordance with yet another embodiment of the invention. In this embodiment, sheet assembly 512 is eonfigured for transferring latent heat, such as described above with reference to FIGURE 37. Thus, sheet assembly 512 includes baffles 668 appropriate for controlling the path of fluids through sheet assembly 512 for providing latent heat transfer. In this embodiment, sheet assembly 512 also includes a first flange 750 and a second flange 752 located at opposite ends of sheet assembly 512. First and second flanges 750 and 752 are used for mounting sheet assembly 5t2 to flanges 602 and 604 of shell 502, as described below with reference to FIGURE 46.

FIGURE 45 illustrates another perspective view of the assembled sheet assembly 512 of FIGURE 43, showing lhe location of temion rods 760 that seal gaskets 762 located between angled corner members 764 and sheets 513 of sheet assembly 512. Tension rods 760 may interact with brackets 766 rigidly coupled to corner members 764, such as by adhesive, braze or weld, for example.

FIGURE 46 illustrates a side view of an assembled heat exchanger assembly 500 including the sheet assembly 512 shown in FIGURES 44-45 in accordance with one embodiment of the invention. First flange 750 is an extension of first end plate 612 of sheet assembly 512. First flange 750 mates with, and is coupled between, flanges 602 and 604 of shell 510 by fasteners 606. Second flange 752 is a ring that couples second end plate 614 of sheet assembly 512 to shell 510. 1,1 particular, second flange 750 is rigidly coupled to second end plate 614 and mates with, and is coupled between, flanges 602 and 604 of shell 510 by fasteners 606.

FIGURES 47 and 48 illustrate cross-sectional views A, B, C, D, E, F and G taken along lines A-A, B-B, C-C, D-D, E-E, F-F and G-G, respectively, shown in FIGURE 46 in accordance with one embodiment of the invention. As shown ia FIGURE 47, view A shows hemispherical cap 600, including flange portion 602. View I3 shows first end plate 612 and first flange 750. As discussed above, first flange 750 of end plate 612 mates with and is coupled to flange portion 602 of cap 600. First end plate 612 may include one or more holes 616 operable to allow pressure to equalize across the surfaces of sheets 513 of sheet assembly 512. View C av_d D show baffles 668a and 668b located in high-pressure chambers 582 and 580, respectively.

As shown in FIGURE 48, view E shows second end plate 614 and cylindrical portion 516 of shell 510, including flange portion 604. Like first end plate 612, second emd plate 614 may include one or more holes 616 operable to allow pressure to equalize across the surfaces of sheets 513 of sheet assembly 512. A push plate 630 may be located at the center of second end plate 614. Push plate 630 may compress sealers 372 (e.g., O-rings or gaskets) located in spacers 362 within sheet assembly, such as described above with reference to FIGURES 28-35, for example. View F shows second flange 752, which comprises a mlg that couples second end plate 614 of sheet assembly 512 to flange portions 602 and 604 of shell 510, as shown in FIGURE 46 and discussed above. Second flange 752 may be flexible to accommodate dimensional changes caused by thermal expansion. View G shows mounting devices (or tracks) 560 coupled [o shell 510 and used to hold sheet assembly 512 in position within, shell 510. Each mounting track 560 may be coupled to shell 510 in any suitable manner, such as by welding or using fasteners, for example.. One or more gaskets (or other snitable sealing device) 634 may be located adjacent each mounting track 560 in order to seal sheet assembly 512 to that mounting track 560.

Atthough embodiments of the invention and their advantages are described in detail, a person skilled in the art could make various alterations, additions, and omissions without departing from the spirit and scope of the present invention.