In order to improve energy utilization rate of biogas engine-driven heat pump (BEHP) systems for wastewater treatment plant, the exergy analysis is applied in this paper. The paper concludes the exergy losses and exergy efficiency of each equipment, and reveals the weak link of energy transformation of the whole system. According to the calculation of one example, the location of maximum exergy loss is the biogas engine-driven, while the location of minimum exergy efficiency is the compressor, which provides powerful theoretic references to improve and optimize BEHP systems for wastewater treatment plant.

With the speeding urbanization process in China, the amount of floating population increases at an unprecedented speed. How to solve the housing security issue now becomes a key indicator for social stability. In this paper, a new low-income housing requirement prediction method is proposed based on stepped leveling of floating population and related evaluation index predictions. Using Logistic retardant population growth model and Todaro method, floating population in the next 5 years is predicted. Then the population is divided into stepped levels to predict housing requirement. Based on the prediction of commercial house price, the method of predicting low-income house demand for different levels in urban areas is given. To demonstrate the proposed model and method, Shanghai Statistical data over the years are used and analyzed.