Comparative Study Of Absorption Refrigeration And Electric Compression Refrigeration In District Energy Systems

With the rapid development of economy and society in China, energy consumptiongrows continuously; energy shortages and the situation of energy conservation and emissionreduction are becoming increasingly serious. Natural gas is a clean and high-quality energy,increasing the proportion of natural gas in primary energy structure in China is helpful toalleviate the pressure of energy shortage and reduce emissions. In recent years, District energysystem(DES) receives wide attention and development because of its feature of improvingenergy efficiency, energy conservation and emission reduction. As a result, which is the betterway of refrigeration in DES between steam absorption refrigeration and electric compressionrefrigeration becomes the focus in engineering field. Therefore, carrying out a study tocompare DES performance when DES selects steam absorption refrigeration versus selectingelectric compression refrigeration has great significance for DES.In this paper, exergy analysis of steam double-effect LiBr/water absorption refrigerationand electric compression refrigeration is carried out. The exergy analysis models of thecomponents in the two refrigeration cycles are introduced, and the performance of the tworefrigeration cycles are investigated and compared based on exergetic efficiency. By thecalculation and comparison of the two refrigeration cycles, it finds that the exergy loss of thecompressor in the electric compression refrigeration is highest. However, the component ofthe maximum exergy loss of the steam double-effect LiBr/water absorption refrigeration is theabsorber. In order to keep exergy from losing, the improving methods for the two refrigerationcycles are proposed.On the basis of the above research, the exergy efficiency and unit exergoeconomic costsof the two refrigeration systems and the energy efficiency of DES are studied and compared.The results show that under the calculation condition, when the steam transmission distance isless than5km, the exergy efficiency of the steam double-effect LiBr/water absorptionrefrigeration system and the energy efficiency of DES selecting steam double-effectLiBr/water absorption refrigeration are higher than that of the electric compressionrefrigeration system. When the steam transmission distance is5km-9.3km, the energyefficiency of DES selecting steam double-effect LiBr/water absorption refrigeration is higher,but the exergy efficiency of the steam double-effect LiBr/water absorption refrigerationsystem is lower than that of the electric compression refrigeration system. Otherwise, electriccompression refrigeration is better for DES. According to the unit exergoeconomic costs, the maximum steam transmission distance when the steam double-effect LiBr/water absorptionrefrigeration system is better varies with the steam exergy price and feed-in tariff. Consideringthe results in this paper synthetically is helpful to select the better way of refrigeration forDES.