\u2022 <\/a>Membrane processes<\/em>, for which reverse osmosis (RO) or electrodialysis (ED) is applied.<\/p>\n\n\n\n The operating principle of phase change processes entails reusing the latent heat of evaporation to preheat the feed while at the same time condensing steam to produce freshwater. The energy\u00a0requirements of these systems are traditionally defined in terms of units of distillate produced per unit mass (kg or lb) of steam or per 2326\u00a0kJ (1000\u00a0Btu) heat input, which corresponds to the latent heat of vaporization at 73\u00a0\u00b0C. This dimensional ratio in kg\/2326\u00a0kJ or lb\/1000\u00a0Btu is known as the performance ratio (PR) (El-Sayed and Silver, 1980). The operating principle of membrane processes leads to the direct production of electricity from solar or wind energy, which is used to drive the plant. Energy consumption is usually expressed in kWhe<\/sub>\/m3<\/sup>\u00a0(Kalogirou, 1997b).<\/p>\n\n\n\n The multi-stage flash (MSF) process is composed of a series of elements, called\u00a0stages<\/em>. In each stage, condensing steam is used to preheat the seawater feed. By fractionating the overall temperature differential between the warm source and seawater into a large number of stages, the system approaches ideal total latent heat recovery. Operation of this system requires pressure gradients in the plant. The principle of operation is shown in\u00a0Figure 8.4. Current commercial installations are designed with 10\u201330 stages (2\u00a0\u00b0C temperature drop per stage).<\/p>\n\n\n\n FIGURE 8.4<\/strong> <\/a>Principle of operation of the multi-stage flash (MSF) system.<\/p>\n\n\n\n A practical cycle representing the MSF process is shown in\u00a0Figure 8.5. The system is divided into heat recovery and heat rejection sections. Seawater is fed through the heat rejection section, which rejects thermal energy from the plant and discharges the product and brine at the lowest possible temperature. The feed is then mixed with a large mass of water, which is recirculated around the plant. This water then passes through a series of heat exchangers to raise its temperature. The water next enters the solar collector array or a conventional brine heater to raise its temperature to nearly the saturation temperature at the maximum system pressure. The water then enters the first stage through an orifice and, in so doing, has its pressure reduced. Since the water was at the saturation temperature for a higher pressure, it becomes superheated and flashes into steam. The vapor produced passes through a wire mesh (demister) to remove any entrained brine droplets and then into the heat exchanger, where it is condensed and drips into a distillate tray. This process is repeated through the plant because both brine and distillate streams flash as they enter subsequent stages that are at successively lower pressures. In MSF, the number of stages is not tied rigidly to the PR required from the plant. In practice, the minimum must be slightly greater than the PR, whereas the maximum is\u00a0imposed by the boiling point elevation. The minimum interstage temperature drop must exceed the boiling point elevation for flashing to occur at a finite rate. This is advantageous because, as the number of stages is increased, the terminal temperature difference over the heat exchangers increases and hence less heat transfer area is required, with obvious savings in plant capital cost (Morris and Hanbury, 1991).<\/p>\n\n\n\n FIGURE 8.5<\/strong> <\/a>An multi-stage flash (MSF) process plant.<\/p>\n\n\n\n MSF is the most widely used desalination process in terms of capacity. This is due to the simplicity of the process, performance characteristics, and scale control (Kalogirou, 1997b). A disadvantage of MSF is that precise pressure levels are required in the different stages; therefore, some transient time is required to establish the normal running operation of the plant. This feature makes the MSF relatively unsuitable for solar energy applications unless a storage tank is used for thermal buffering.<\/p>\n\n\n\n For the MSF system (El-Sayed and Silver, 1980),<\/p>\n\n\n\n where<\/a><\/p>\n\n\n\n <\/a>M<\/em>d<\/sub> = mass rate of distillate (kg\/h).<\/p>\n\n\n\n <\/a>M<\/em>f<\/sub> = mass rate of feed (kg\/h).<\/p>\n\n\n\n <\/a>L<\/em>v<\/sub> = average latent heat of vaporization (kJ\/kg).<\/p>\n\n\n\n <\/a>c<\/em>p<\/sub> = mean specific heat under constant pressure for all liquid streams (kJ\/kg K).<\/p>\n\n\n\n <\/a>N<\/em> = total number of stages or effects.<\/p>\n\n\n\n The flashing temperature range, \u0394F<\/em>, according to the temperatures shown in\u00a0Figure 8.5, is given by:<\/p>\n\n\n\n where<\/a><\/p>\n\n\n\n <\/a>T<\/em>h<\/sub> = top brine temperature (K).<\/p>\n\n\n\n <\/a>T<\/em>bN<\/em><\/sub> = temperature of brine in the last effect (K).<\/p>\n\n\n\n <\/a>T<\/em>b1<\/sub> = temperature of brine in first effect (K).<\/p>\n\n\n\n <\/a>It should be noted that the rate of external feed per unit of product M<\/em>f<\/sub>\/M<\/em>d<\/sub> is governed by the maximum brine concentration. Therefore,<\/p>\n\n\n\n where<\/a><\/p>\n\n\n\n <\/a>y<\/em>bN<\/em><\/sub> = mass fraction of salts in brine in the last effect (dimensionless).<\/p>\n\n\n\n <\/a>y<\/em>f<\/sub> = mass fraction of salts of feed (dimensionless).<\/p>\n\n\n\n The total thermal load per unit product is obtained by adding all loads,\u00a0Q<\/em>, and approximating (N<\/em>\u00a0\u2212\u00a01)\/N<\/em>\u00a0=\u00a01 and is given by (El-Sayed and Silver, 1980):<\/p>\n\n\n\n where<\/a><\/p>\n\n\n\n <\/a>M<\/em>r<\/sub> = mass rate of recirculated brine (kg\/h).<\/p>\n\n\n\n <\/a>T<\/em>o<\/sub> = environmental temperature (K).<\/p>\n\n\n\n EXAMPLE 8.4<\/p>\n\n\n\n Estimate M<\/em>f<\/sub>\/M<\/em>d<\/sub> ratio for an MSF plant, which has 35 stages, brine temperature in first effect is 71 \u00b0C, and the temperature of the brine in the last effect is 35 \u00b0C. The mean latent heat is 2310 kJ\/kg and the mean specific heat is 4.21 kJ\/kg K.<\/p>\n\n\n\n Solution<\/p>\n\n\n\n From Eq.\u00a0(8.36),<\/p>\n\n\n\n From Eq.\u00a0(8.35),<\/p>\n\n\n\n The brine recycle flow rate can be obtained from the brine heater energy balance. The energy given by the heating steam (subscript s) is equal to:<\/p>\n\n\n\n By dividing Eq.\u00a0(8.39)\u00a0by the mass rate of distillate (M<\/em>d<\/sub>) and rearranging:<\/p>\n\n\n\n The term\u00a0M<\/em>d<\/sub>\/M<\/em>r<\/sub>\u00a0is the system performance ratio (PR). The cooling water flow rate (subscript cw) is obtained from the energy balance of the whole system shown in\u00a0Figure 8.5\u00a0which gives:<\/p>\n\n\n\n Dividing Eq.\u00a0(8.41)\u00a0by the mass rate of distillate (M<\/em>d<\/sub>):<\/p>\n\n\n\n where as before\u00a0M<\/em>d<\/sub>\/M<\/em>r<\/sub>\u00a0is the system PR and the ratio\u00a0M<\/em>d<\/sub>\/M<\/em>f<\/sub>\u00a0is called the system\u00a0conversion ratio<\/em>\u00a0(CR). Therefore, Eq.\u00a0(8.42)\u00a0can be written as:<\/p>\n\n\n\n It should be noted that the term 1\/CR is given by Eq.\u00a0(8.37).<\/p>\n\n\n\n Moustafa et al. (1985)\u00a0report on the performance of a 10\u00a0m3<\/sup>\/day solar MSF desalination system tested in Kuwait. The system consisted of 220\u00a0m2<\/sup>\u00a0parabolic trough collectors (PTCs), 7000\u00a0l of thermal storage, and a 12-stage MSF desalination system. The thermal storage system was used to level off the thermal energy supply and allowed the production of freshwater to continue during periods of low solar radiation and nighttime. The output of the system is reported to be more than 10 times the output of solar stills for the same solar collection area.<\/p>\n\n\n\n The multiple-effect boiling (MEB) process shown in\u00a0Figure 8.6\u00a0is also composed of a number of elements, which are called\u00a0effects<\/em>. The steam from one effect is used as heating fluid in another effect, which, while condensing, causes evaporation of a part of the salty solution. The produced steam goes through the following effect, where, while condensing, it makes some of the other solution evaporate, and so on. For this procedure to be possible, the heated effect must be kept at a pressure lower than that of the effect from which the heating steam originates. The solutions condensed by all effects are used to preheat the feed. In this process, vapor is produced by flashing and by boiling, but the majority of the distillate is produced by boiling. Unlike an MSF plant, the MEB process usually operates as a once-through system without a large mass of brine recirculating around the plant. This design reduces both pumping requirements and scaling tendencies (Kalogirou, 1997b).<\/p>\n\n\n\n FIGURE 8.6<\/strong> <\/a>Principle of operation of a multiple-effect boiling (MEB) system.<\/p>\n\n\n\n As with the MSF plant, the incoming brine in the MEB process passes through a series of heaters, but after passing through the last of these, instead of entering the brine heater, the feed enters the top effect, where the heating steam raises its temperature to the saturation temperature for the effect pressure. Further amounts of steam, from either a solar collector system or a conventional boiler, are used to produce evaporation in this effect. The vapor then goes, in part, to heat the incoming feed and, in part, to provide the heat supply for the second effect, which is at a lower pressure and receives its feed from the brine of the first effect. This process is repeated all the way through (down) the plant. The distillate also passes down the plant. Both the brine and the distillate flash as they travel down the plant due to progressive reduction in pressure (Kalogirou, 1997b).<\/p>\n\n\n\n There are many possible variations of MEB plants, depending on the combinations of heat transfer configurations and flow sheet arrangements used. Early plants were of the submerged tube design and used only two or three effects. In modern systems, the problem of low evaporation rate has been resolved by using thin film designs with the feed liquid distributed on the heating surface in the form of a thin film instead of a deep pool of water. Such plants may have vertical or horizontal tubes. The vertical tube designs are of two types: climbing film, natural, and forced circulation type or long tube vertical (LTV), straight falling film type. In LTV plants, as shown in\u00a0Figure 8.7, the brine boils inside the tubes and the steam condenses outside. In the horizontal tube, falling film design, the steam condenses inside the tube with the brine evaporating on the outside.\u00a0With multiple evaporation, the underlying principle is to use the available energy of the leaving streams of a single-evaporation process to produce more distillate.<\/p>\n\n\n\n FIGURE 8.7<\/strong> <\/a>Long tube vertical MEB plant.<\/p>\n\n\n\n In the case of the MEB system, the ratio\u00a0M<\/em>f<\/sub>\/M<\/em>d<\/sub>\u00a0is fixed by the maximum allowable brine concentration to a value on the order of 2 and is given by (El-Sayed and Silver, 1980):<\/p>\n\n\n\n where<\/a><\/p>\n\n\n\n <\/a>f<\/em>n<\/sub> = mass rate of distillate obtained by flashing per stage (kg\/h).<\/p>\n\n\n\n <\/a>\u0394t<\/em>n<\/sub> = temperature drop between two effects consisting of the heat transfer temperature difference and an augmented boiling point elevation (K).<\/p>\n\n\n\n The total thermal load per unit product obtained by adding all loads,\u00a0Q<\/em>, and dividing by\u00a0M<\/em>d<\/sub>\u00a0is given by (El-Sayed and Silver, 1980):<\/p>\n\n\n\n where<\/a><\/p>\n\n\n\n <\/a>\u03b5<\/em> = boiling point rise augmented by vapor frictional losses (K).<\/p>\n\n\n\n <\/a>\u0394t<\/em>t<\/sub> = terminal temperature difference in feed heater condenser (K).<\/p>\n\n\n\n According to the analysis given by\u00a0Al-Sahali and Ettouney (2007)\u00a0who presented a modified analysis of\u00a0Geankoplis (2003), the temperature drop across all effects is given by:<\/p>\n\n\n\n Where subscript t is for total and \u0394T<\/em><\/sub> represents temperature losses in each evaporation effect. Temperature drop in the first effect is given by:<\/p>\n\n\n\n And the temperature drop in effects 2-N is given by:<\/p>\n\n\n\n The brine temperature in the first effect is obtained from:<\/p>\n\n\n\n And the brine temperature in the effects 2-N is given by:<\/p>\n\n\n\n The distillate flow rate in the first effect is:<\/p>\n\n\n\n <\/a>Distillate flow rate in the effects 2-N is:<\/p>\n\n\n\n The brine flow rate in various effects is given by:<\/p>\n\n\n\n where<\/a><\/p>\n\n\n\n <\/a>y<\/em>cw<\/sub> = mass fraction of salts in cooling seawater (dimensionless).<\/p>\n\n\n\n And the feed rate in various effects is given by:<\/p>\n\n\n\n The heating steam flow rate is given by:<\/p>\n\n\n\n The flow rate of the cooling seawater is given by:<\/p>\n\n\n\n With respect to the size of the equipment, the heat transfer area in the first effect is given by:<\/p>\n\n\n\n The heat transfer area in the effects 2-N is given by:<\/p>\n\n\n\n And the heat transfer area of the condenser (subscript c) is given by:<\/p>\n\n\n\n where<\/p>\n\n\n\n LMTD = log mean temperature difference given by:<\/p>\n\n\n\n in which \u0394T<\/em>1<\/sub> and \u0394T<\/em>2<\/sub> represent the temperature difference between the two fluids at the inlet and outlet of the condenser. It makes no difference which side of the condenser is designated as the inlet or the outlet.<\/p>\n\n\n\n Another type of MEB evaporator is the multiple-effect stack (MES). This is the most appropriate type for solar energy applications. It has a number of advantages, the most important of which is its\u00a0stable operation between virtually 0% and 100% output, even when sudden changes are made, and its ability to follow a varying steam supply without upset. In\u00a0Figure 8.8, a four-effect MES evaporator is shown. Seawater is sprayed into the top of the evaporator and descends as a thin film over the horizontally arranged tube bundle in each effect. In the top (hottest) effect, steam from a steam boiler or a solar collector system condenses inside the tubes. Because of the low pressure created in the plant by the vent\u2013ejector system, the thin seawater film boils simultaneously on the outside of the tubes, thus creating new vapor at a lower temperature than the condensing steam.<\/p>\n\n\n\n FIGURE 8.8<\/strong> <\/a>Schematic of the MES evaporator.<\/p>\n\n\n\n The seawater falling to the floor of the first effect is cooled by flashing through nozzles into the second effect, which is at a lower pressure. The vapor made in the first effect is ducted into the inside of the tubes in the second effect, where it condenses to form part of the product. Furthermore, the condensing warm vapor causes the external cooler seawater film to boil at the reduced pressure.<\/p>\n\n\n\n The evaporation\u2013condensation process is repeated from effect to effect in the plant, creating an almost equal amount of product inside the tubes of each effect. The vapor made in the last effect is\u00a0condensed on the outside of a tube bundle cooled by raw seawater. Most of the warmer seawater is then returned to the sea, but a small part is used as feedwater to the plant. After being treated with acid to destroy scale-forming compounds, the feedwater passes up the stack through a series of preheaters that use a little of the vapor from each effect to raise its temperature gradually, before it is sprayed into the top of the plant. The water produced from each effect is flashed in a cascade down the plant so that it can be withdrawn in a cool condition at the bottom of the stack. The concentrated brine is also withdrawn at the bottom of the stack. The MES process is completely stable in operation and automatically adjusts to changing steam conditions, even if they are suddenly applied, so it is suitable for load-following applications. It is a once-through process that minimizes the risk of scale formation without incurring a large chemical scale dosing cost. The typical product purity is less than 5\u00a0ppm TDS and does not deteriorate as the plant ages. Therefore, the MEB process with the MES-type evaporator appears to be the most suitable for use with solar energy.<\/p>\n\n\n\n A 14-effect MEB plant with a nominal output of 3\u00a0m3<\/sup>\/h coupled with 2672\u00a0m2<\/sup>\u00a0PTCs was reported by\u00a0Zarza et al. (1991a,\u00a0b). The system is installed at the Plataforma Solar de Almeria in southern Spain. It also incorporates a 155\u00a0m3<\/sup>\u00a0thermocline thermal storage tank. The circulated fluid through the solar collectors is a synthetic oil heat transfer fluid. The PR obtained by the system varies from 9.3 to 10.7, depending on the condition of the evaporator tube\u2013bundle surfaces. The authors estimated that the efficiency of the system can be increased considerably by recovering the energy wasted when part of the cooling water in the final condenser is rejected. Energy recovery is performed with a double-effect absorption heat pump.<\/p>\n\n\n\n El-Nashar (1992)\u00a0gives details of an MES system powered with 1862\u00a0m2<\/sup>\u00a0evacuated tube collectors. The system is installed in Abu Dhabi, United Arab Emirates. A computer program was developed for the optimization of the operating parameters of the plant that affect its performance, that is, the collector area in service, the high-temperature collector set point, and the heating water flow rate. The maximum daily distillate production corresponding to the optimum operating conditions was found to be 120\u00a0m3<\/sup>\/day, which can be obtained for 8\u00a0months of the year.<\/p>\n\n\n\n Exergy analysis, based on actual measured data of the MES plant installed in the solar plant near Abu Dhabi, is presented by\u00a0El-Nashar and Al-Baghdadi (1998). The exergy destruction was calculated for each source of irreversibility. The major exergy destruction was found to be caused by irreversibilities in the different pumps, with the vacuum pump representing the main source of destruction.<\/p>\n\n\n\n Major exergy losses are associated with the effluent streams of distillate, brine blowdown, and seawater. Exergy destruction due to heat transfer and pressure drop in the different effects, the preheaters, and the final condenser and in the flashing of the brine and distillate between the successive effects represents an important contribution to the total amount of exergy destruction in the evaporator.<\/a><\/p>\n\n\n\n In a vapor compression (VC) plant, heat recovery is based on raising the pressure of the steam from a stage by means of a compressor (see\u00a0Figure 8.9). The condensation temperature is thus increased and the steam can be used to provide energy to the same stage it came from or to other stages (Mustacchi and Cena, 1978). As in a conventional MEB system, the vapor produced in the first effect is used as the heat input to the second effect, which is at a lower pressure. The vapor produced in the last effect is then passed to the vapor compressor, where it is compressed and its saturation temperature is raised before it is returned to the first effect. The compressor represents the major energy input to the system, and since the latent heat is effectively recycled around the plant, the process has the potential for delivering high PR values (Morris and Hanbury, 1991).<\/p>\n\n\n\n FIGURE 8.9<\/strong> <\/a>Principle of operation of a vapor compression (VC) system.<\/p>\n\n\n\n Parametric cost estimates and process designs have been carried out and show that this type of plant is not particularly convenient, unless it is combined with an MEB system. Furthermore, it appears that the mechanical energy requirements have to be provided with a primary drive, such as a diesel engine, and cooling the radiator of such an engine provides more than enough heat for the thermal requirements of the process, making the solar collector system redundant (Eggers-Lura, 1979). Therefore, the VC system can be used in conjunction with an MEB system and operated at periods of low solar radiation or overnight.<\/p>\n\n\n\n Vapor compression systems are subdivided in two main categories: mechanical vapor compressor (MVC) and thermal vapor compressor (TVC) systems. MVC systems employ a mechanical compressor to compress the vapor, whereas thermal ones utilize a steam jet compressor. The main problems associated with the MVC process are (Morris and Hanbury, 1991):<\/p>\n\n\n\n 1. <\/a>Vapor-containing brine is carried over into the compressor and leads to corrosion of the compressor blades.<\/p>\n\n\n\n 2. <\/a>There are plant-size limitations because of limited compressor capacities.<\/p>\n\n\n\n8.4.1 The multi-stage flash process<\/h3>\n\n\n\n
![\"image\"\/](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xf08-04-9780123972705.jpg\")
<\/figure>\n\n\n\n![\"image\"\/](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xf08-05-9780123972705.jpg\")
<\/figure>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi48.png\")
(8.35)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi49.png\")
(8.36)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi50.png\")
(8.37)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi51.png\")
(8.38)<\/strong><\/p>\n\n\n\n![\"image\"\/](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi52.png\")
<\/figure>\n\n\n\n![\"image\"\/](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi53.png\")
<\/figure>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi54.png\")
(8.39)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi55.png\")
(8.40)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi56.png\")
(8.41)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi57.png\")
(8.42)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi58.png\")
(8.43)<\/strong><\/p>\n\n\n\n8.4.2 The multiple-effect boiling process<\/h3>\n\n\n\n
![\"image\"\/](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xf08-06-9780123972705.jpg\")
<\/figure>\n\n\n\n![\"image\"\/](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xf08-07-9780123972705.jpg\")
<\/figure>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi59.png\")
(8.44)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi60.png\")
(8.45)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi61.png\")
(8.46)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi62.png\")
(8.47)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi63.png\")
(8.48)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi64.png\")
(8.49)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi65.png\")
(8.50)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi66.png\")
(8.51)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi67.png\")
(8.52)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi68.png\")
(8.53)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi69.png\")
(8.54)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi70.png\")
(8.55)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi71.png\")
(8.56)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi72.png\")
(8.57)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi73.png\")
(8.58)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi74.png\")
(8.59a)<\/strong><\/p>\n\n\n\n![\"image\"](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xsi75.png\")
(8.59b)<\/strong><\/p>\n\n\n\n![\"image\"\/](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xf08-08-9780123972705.jpg\")
<\/figure>\n\n\n\n8.4.3 The vapor compression process<\/h3>\n\n\n\n
![\"image\"\/](\"https:\/\/learning.oreilly.com\/api\/v2\/epubs\/urn:orm:book:9780123972705\/files\/images\/F00008Xf08-09-9780123972705.jpg\")
<\/figure>\n\n\n\n