Allocation optimization of two-stage compression-absorption heat exchanger

Abstract

Space heating demand of buildings is a significant component of global energy consumption. Lowering the operating temperatures can increase the overall energetic and exergetic efficiencies. To obtain a lower return water temperature, researchers have proposed a variety of approaches. Absorption heat exchanger is an effective way to reduce return water temperature. However, in two-stage absorption heat exchanger and compression-absorption heat exchanger, extra temperature difference exists in evaporator of absorption heat pump. To eliminate the extra temperature difference, optimized compression-absorption heat exchanger is put forward in the article. Based on the typical case, the energy saving rate of optimized compression-absorption heat exchanger can reach 17.9 %, and the principle of energy saving is analyzed in the article, the key point is the extra temperature difference and the cooling capacity of evaporator of absorption heat pump. Further, the energy savings of the optimized heat changer in different supply and return temperature of primary and secondary network is analyzed. Main factors affecting the energy saving rate are primary network supply temperature and secondary network supply-return temperature difference. As the result, when primary network supply temperature is 130 °C and secondary network supply and return temperature is 50 °C and 40 °C, energy saving rate can reach 28.4 %.