【導(dǎo)讀】循環(huán)中驅(qū)動(dòng)裝置的目的是完成整個(gè)循環(huán)，在機(jī)械功驅(qū)動(dòng)蒸氣壓縮制冷循環(huán)中，此驅(qū)動(dòng)裝置。機(jī)械功驅(qū)動(dòng)蒸氣壓縮制冷循環(huán)的原理在2-2部分已經(jīng)做了簡(jiǎn)單的描述，整個(gè)循環(huán)。的流程將會(huì)在本章做詳細(xì)的說(shuō)明。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。性、不易燃和非爆炸性的制冷劑，這些問(wèn)題都可以得到避免。壓縮機(jī)使膨脹閥的兩端存在著一個(gè)壓差并使制冷。劑在膨脹閥中穩(wěn)定的流動(dòng)。壓縮機(jī)維持著系統(tǒng)的循環(huán)從而保持連續(xù)的制冷。這里以制冷劑R134a為例，假定離開(kāi)蒸發(fā)器的制冷劑溫度為-20℃，冷凝溫度為40℃。403，R134a的熱力參數(shù)可以從P-h圖或熱

　　

【正文】 鍋爐或發(fā)生系統(tǒng)產(chǎn)生的 蒸氣 或熱水。 , a doubleeffect absorption cycle [10] 圖 雙效吸收式循環(huán) If vapor temperature leaving the generator (boiler) is high, the vapor can be used to heat other generators. In the absorption industry, ―effect‖ is used to refer how many times the heat energy is utilized. In a singleeffect absorption chiller, the heat carried away by the vapor evolved from the generator is rejected in the condenser, where heat is only use once. In a multipleeffect absorption chiller, some of this energy is used to generate more refrigerant vapor before rejected to the surrounding. The more vapor generated per unit of heat or fuel input, the greater the cooling capacity, hence, the higher the overall operating efficiency. Multipleeffect chillers are more efficient than singleeffect chillers, but they require high temperature heat source. Singleeffect chillers may be driven by hot water ranging from 75 to 150℃ , but doubleeffect chillers require either direct heat from a gas flame or highpressure steam. 如果離開(kāi)發(fā)生器的蒸氣溫度過(guò)高，這些蒸氣可以用來(lái)加熱另一個(gè)發(fā)生器。在吸收式工藝中中，效果用來(lái)表示熱量的利用率。在單效吸收裝置中由發(fā)生器產(chǎn)生的蒸氣所帶的熱在冷凝器中被放到環(huán)境中，這里的熱只利用一次。多效吸收裝置中，在被排放到環(huán)境之前，這些熱量中的一些用來(lái)產(chǎn)生更多的制冷劑蒸氣。單位熱或燃料產(chǎn)生的蒸氣越多，冷卻能力越大，總體的運(yùn)行效率就越高。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。單效裝置可以在 75℃ 到 150℃ 之間的熱水驅(qū)動(dòng)。但是雙效要求由氣體 火焰或高壓 蒸氣 直接驅(qū)動(dòng)。 shows a doubleeffect absorption cycle. Doubleeffect absorption machines uses two generators paired with a single condenser, absorber, and evaporator. The highertemperature generator (1) is called the first stagegenerator. The refrigerant vapor produced in the generator (1) is then used to desorb additional refrigerant (water) from a lowertemperature, the secondstage generator (2). So heat energy from the first stage is recovered and is utilized in the second stage. Consequently, a doubleeffect absorption cycle is more efficient than a singleeffect one. For example of a LiBr absorption system used for air conditioning, the heat ratio ? of absorption chillers ranges from to for indirectfired singleeffect systems, to about for indirectfired doubleeffect units. [11] 圖 57所示是雙效吸收循環(huán)，雙效吸收裝置有兩個(gè)發(fā)生器和與之相配的冷凝器，吸收器和蒸發(fā)器。高溫發(fā)生器 (1)叫做第一級(jí)發(fā)生器。在發(fā)生器 (1)中產(chǎn)生的制冷劑蒸氣被用來(lái)在第二級(jí)發(fā)生器 (2)中放出附加的制冷劑蒸氣。所以來(lái)自第一級(jí)的熱量在第二級(jí)中被回收和利用了。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。比如說(shuō)直接加熱的單效空調(diào)用溴化鋰制冷循環(huán)的吸收裝置的熱力系數(shù)在 ，而雙效單元可以達(dá)到 . , a Tripleeffect absorption chillerheater (. Hightemperature, . Intermediatetemperature, . Lowtemperature) 圖 三效吸收式冷水機(jī)組 (. –高溫 , . –中溫 , . –低溫 ) shows a tripleeffect absorption chillerheater which has three generators: hightemperature, intermediatetemperature and lowtemperature. The structure is similar to that of conventional doubleeffect systems except for the additional generator that is included. The heat ratio ? , or cooling coefficient of performance (COP), higher than that of doubleeffect systems can be obtained by heating the generators with a hightemperature heat source such as city gas and then utilizing cascading heat in the absorption cycle process. The hightemperature generator in a tripleeffect system is exposed to a higher temperature and higher pressure than in a doubleeffect system. Therefore, the development of corrosion inhibition technology and safety improvement technologies, such as a novel oncethrough type hightemperature generator, emerged as key issues. At the same time, development of more pact and higher efficiency ponents, latent heat utilization, and control optimization are also technological challenges to be overe. [12] 圖 58所示是具有三個(gè)發(fā)生器的三效吸收式裝置，三個(gè)發(fā)生器是：高溫，中文和低溫發(fā)生器。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。用像城市煤氣這樣的高溫?zé)嵩磥?lái)加熱發(fā)生器，在吸收過(guò)程中被逐級(jí)吸收，所以其熱力系數(shù)或制冷系數(shù)比雙效的高。三效系統(tǒng)中的高溫發(fā)生器比雙效具有更高的溫度和壓力。因此，防腐技術(shù)和提高安全性技術(shù)的發(fā)展成了關(guān)鍵，比如直流型高溫發(fā)生器。同時(shí)，緊湊高效部件的開(kāi)發(fā)，潛熱利用，控制優(yōu)化也是需要克服的挑戰(zhàn)。 Some disadvantages associated with lithium bromide absorption refrigeration systems are: the risk of crystallization of solution at high concentrations。 the corrosion in the system can occur. Lithium bromide, a highly corrosive brine, readily attacks ferrous metals such as steel. The corrosion process generates hydrogen gas that reduces the internal vacuum inside the evaporator, which results in the unit operating poorly. In addition, the debris resulting from the corrosion fouls narrow openings in spray headers, heat exchangers, etc. In order to enhance the performance of the working fluid, over the past 40 years a series of elaborate proprietary formulations have been built around the lithium bromidewater system so that its crystallization temperature can be lowered and its corrrosivity to metals can be reduced. Some anic salts of sodium and potassium such as potassium formate can be added to the lithium bromide water system and it has been proved that it can improve the characteristics and the efficiency of the refrigeration cycle. 溴化鋰吸收式制冷系統(tǒng)的不利因素有：高濃度溶液的結(jié)晶風(fēng)險(xiǎn)，蒸發(fā)器中可能會(huì)發(fā)生腐蝕。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。腐蝕過(guò)程中產(chǎn)生的氫氣可以減小蒸發(fā)器的內(nèi)部真空度，使機(jī)組的運(yùn)行工況變差。而且，腐蝕所形成的碎片使噴淋水頭，換熱器等的通道變窄。為了提高工作流體的性能，近四十年來(lái)，圍繞 LiBrH2O系統(tǒng)建立了一系列精心研究的專用公式，是結(jié)晶溫度更低，對(duì)金屬的腐蝕作用更小。 LiBrH2O 系統(tǒng)可以加入一些鈉和鉀的有機(jī)鹽比如甲酸鉀，已經(jīng)證明這可以提高制冷循環(huán)的性能和效率。 7. The AmmoniaWater Absorption System 7. 氨水吸收式系統(tǒng) (1) Principles of the ammoniawater absorption system [13] (1) 氨水吸收式系統(tǒng)的原理 In ammoniawater absorption system, water is a absorbent, ammonia is a refrigerant. Operation of the refrigeration cycle is conventional with high pressure refrigerant entering the receiver from the condenser before passing to an expansion valve and an evaporator where heat is absorbed from the process. The remaining items in the system replace the conventional pressor to achieve ―thermal‖ pression in three steps: 在氨水吸收式系統(tǒng)中，水是吸收劑，氨氣是制冷劑。制冷循環(huán)是常規(guī)的 ，從冷凝器來(lái)的高壓制冷劑進(jìn)入接收器，接著通過(guò)膨脹閥和發(fā)生吸熱過(guò)程的蒸發(fā)器 。系統(tǒng)的剩余部分取代常規(guī)壓縮機(jī)分以下三步來(lái)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(guò)程 2) Transport of the strong ammonia water solution from evaporator pressure to condenser pressure by a pump. 2) 泵將濃