【正文】 溴化鋰是一種腐蝕性很強(qiáng)的鹽，可以輕易地腐蝕像鋼這種金屬。多效裝置的效率比單效裝置的高，但它要求更高的熱源溫度。這個(gè)數(shù)據(jù)假設(shè) 0℃ 時(shí)液態(tài)水和無水溴化鋰的焓都為 0。發(fā)生器中的溶液被高溫?zé)嵩吹臒崃浚?Qb）加熱到沸騰并釋放制冷劑（水），同時(shí)溶液被濃縮。 the ordinate on the righthand is temperature in linear scale, shows the saturation temperature of pure water which has the same vapor pressure as a BrLi solution at the temperature given by the abscissa. The line of pure water is also shown in the figure, which is corresponding to a solution of 0?? , all the points on the line of pure water have the same values of temperature both on the abscissa and on the ordinate on the righthand. 溴化鋰水溶液的蒸氣壓力由它的溫度和質(zhì)量分?jǐn)?shù)決定，它們的關(guān)系如圖 53。從發(fā)生器來的熱的稀溶液將熱量傳給來自吸收器的濃溶液。這個(gè)系統(tǒng)早期的發(fā)展可以追溯的 100年前。 Mechanical operated vapor pression refrigeration cycle is the most main content in this book。 and reasonable price. There are some difficulties with security during its operation, but they can be avoided by properly selecting materials and by improving equipment, as well as by choosing appropriate noncorrosive, nonflammable, and nonexplosive refrigerants. 機(jī)械功驅(qū)動(dòng) 蒸氣 壓縮制冷循環(huán)是最常用的制冷循環(huán)，與其他形式的制冷系統(tǒng)相比，它的優(yōu)點(diǎn)包括系統(tǒng)結(jié)構(gòu)緊湊；較高的 COP 值；系統(tǒng)運(yùn)轉(zhuǎn)安全、可靠、靈活；較易維修；價(jià)格合理。 size: ) 第五章． 蒸氣 及氣體制冷循環(huán) 51. Mechanical Operated Vapor Compression Refrigeration Cycle 韓志明 蒸氣 壓縮制冷循環(huán) 1. Introduction of mechanical operated vapor pression refrigeration cycle 蒸氣 壓縮制冷循環(huán)簡(jiǎn)介 In chapter 2, the principals of vapor pression refrigeration cycle have been described. It is stated that almost all the refrigeration cycle consists of four main ponents. One of them is the driving devices of refrigerant circulation in order to plete the cycle. And in mechanical vapor pression refrigeration cycle the driving device is a vapor pressor. A brief statement of the principles of mechanical refrigeration was given in section 22, and a detailed explanation of the full cycle of operations will be presented in this section. 機(jī)械功驅(qū)動(dòng) 蒸氣 壓縮制冷循環(huán)的原理在第二章已經(jīng)描述了，幾乎所有的制冷循環(huán)都包含四個(gè)主要部件。 Here take the Refrigerant R134a as an example. The refrigerant leaves the evaporator at the temperature of 20℃ and has a condensing temperature of 40℃ . 這里以制冷劑 R134a為例，假定離開蒸發(fā)器的制冷劑溫度為 20℃ ，冷凝溫度為 40℃ 。 There are three kinds of vapor pression refrigeration cycles that can be driven by thermal energy. They are: the absorption refrigeration cycle, the adsorption refrigeration cycle and vapor jet refrigeration cycle. These cycles share similar technologies that are used in the vapor pression refrigeration cycle, ., throttling evaporating and condensing. but they are driven by thermal energy. These refrigeration cycles will discussed in this chapter. 有三種蒸氣壓縮式制冷循環(huán)可以用熱能來驅(qū)動(dòng)。在 蒸氣 吸收式制冷系統(tǒng)中常用的工質(zhì)是氨水溶液和溴化鋰溶液。在氨水吸收式系統(tǒng)中，水作為制冷劑會(huì)蒸發(fā)，所以要用精餾除去。 , the vapor pressure of solutions of LiBr in water [6] 圖 53, 溴化鋰水溶液的蒸氣壓力 , the saturated vapor pressure table of pure water [7] 表 51, 水的飽和 蒸氣 壓力表 Temperature Co Saturated Pressure mbar Temperature Co Saturated Pressure mbar Temperature Co Saturated Pressure mbar Temperature Co Saturated Pressure mbar 1 11 21 31 2 12 22 32 3 13 23 33 4 14 24 34 5 15 25 35 6 16 26 36 7 17 27 37 8 18 28 38 9 19 29 39 10 20 30 40 50 4. Basic Lithium bromidewater absorption refrigeration system —水吸收式制冷基本循環(huán) The diagram shown in is a basic lithiumbromide vapor absorption refrigeration system. A basic H2O–LiBr absorption refrigeration system consists of 8 main ponents. Apart from the evaporator, the condenser and the expansion valve which are found in a mechanical powered vapor pression refrigerator, other five ponents, namely, a pump, and absorber, a generator, a heat exchanger and a valve fulfill the function of ―thermal pressor‖: 圖 54所示是溴化鋰 —水吸收式制冷基本循環(huán)。 , a singleeffect lithium bromidewater absorption refrigeration system [8] 圖 55單 效溴化鋰吸收式系統(tǒng) 5. Analysis for a basic absorption refrigeration system (1) Circulation factor (1) 循環(huán)因素 In an absorption refrigeration system, the solution changes its mass fractions in the absorption process. For the lithium bromide absorption system, the mass fractions before and after absorption are denoted by s? and w? , respectively. An important quantity in the calculation of an absorption system is the mass flow rate of the strong solution which is needed to absorb unit mass flow rate of vapor from the evaporator. This quantity is called the circulation factor λ. It can be determined by the concentrations of the strong and weak solutions. From the definition of the circulation factor, after absorption, λ mass flow rate of the solution bees λ+1. Since the mass of lithium bromide in the solution does not change in the absorption process, therefore, the following equation exists 在吸收式制冷系統(tǒng)的吸收過程中，溶液的質(zhì)量分?jǐn)?shù)發(fā)生改變。直接加熱的制冷裝置包括一個(gè)燒天然氣或其他燃料的 燃燒器，燃燒器是用來產(chǎn)生吸收過程所需的熱量的。除了增加了一個(gè)發(fā)生器外，其結(jié)構(gòu)和普通的雙效系統(tǒng)一樣。系統(tǒng)的剩余部分取代常規(guī)壓縮機(jī)分以下三步來完成熱壓縮： 1) Absorption of the ammonia vapor in a weak ammoniawater solution at evaporation pressure. 1) 稀氨水溶液在蒸發(fā)壓下吸收氨蒸氣的過程 2) Transport of the strong ammonia water solution from evaporator pressure to condenser pressure by a pump. 2) 泵將濃氨。所以，雙效吸收式循環(huán)比單效吸收式循環(huán)有更高的效率。 kgkJh /138 ?? 。在吸收式制冷系統(tǒng)中，泵所做的壓縮功只消耗很少的一部分機(jī)械功。從表 51中可以看到 5176。C以上；而氨水吸收式制冷循環(huán)可以在 0186。 , essential ponents of the vapor absorption cycle 圖 52, 蒸氣吸收循環(huán)的主要部分 The main ponents of a basic absorption system are shown diagrammatically in Comparing the left part of , it can be seen that the condenser, expansion valve and evaporator in these two cycles are the same, the mechanical pressor, however, is replaced by a thermal pressor which consists of absorber, solution pump, generator (or boiler) and liquid valve. This group of ponents ?sucks‘ vapor from the evaporator, and delivers high pressure vapor to the condenser, just as the mechanical pressor does but the vapor is actually absorbed by a liquid absorbent . Aqua ammonia and aqua lithium bromide so