Energy efficiency analysis of groundwater source heat pump heating system in cold area biogas project

Abstract: Under the condition of low ambient temperature in the cold region of the northern China, in the event that biogas project really wants to run normally, it needs to be heated by external heat source Choosing a reasonable heating system for the biogas engineering can not only make the heating system of biogas project more effective and reasonable, but also improve the utilization rate of energy. In addition, choosing a reasonable heating system for biogas engineering is truly the typical practical problem that must be solved to realize the low energy consumption and high output of biogas engineering. According to the application example of the heat pump heating system with the groundwater resource in the biogas project, an energy efficiency analysis model taking exergy efficiency, thermal efficiency, and energy level coefficients as the evaluation criterion for the biogas project heating system was established. Through the measured parameters of ground water source heat pump heating system, the results are obtained as the follows: The user system's exergy efficiency of the biogas project is 97.8%; The exergy efficiency of the groundwater source heat pump unit is 13.4%; The total exergy efficiency of the biogas project heating system is 13.1%; The total thermal efficiency of the heating system is 85.3%; the energy level coefficient of the user's heat consumption in the biogas project is 0.161; the energy level coefficient of the user's supply heat capacity is 0.164, as well as the energy level coefficient of the groundwater source heat pump unit is 0.567. The results indicated that the application of ground water source heat pump heating system in biogas engineering is practical and feasible. For users of low grade thermal energy of the biogas project, the exergy efficiency of using low temperature water for heating is relatively higher, and the process of energy use is quite scientific and reasonable. Moreover, the heat pump unit system can not only recover the low-grade heat energy from the groundwater, but also save the high quality electric energy in a feasible way, so that the effective utilization degree for the amount of energy used in the heating system can be very high, however, there still exists a difference in the quality of supply and demand between the heat source and the users, and the further improvement is needed in the use process of energy quality. It is suggested that the heating system of biogas engineering should adopt the heating mode matching the energy level and use the low grade heat source to heat the biogas project and evaluate the process of energy utilization synthetically. The above conclusion can be used as a reference for selecting a reasonable heating mode for biogas engineering in the future.