Simulation And Optimum Matching On Gas Engine Driven Heat Pumps

The gas engine driven heat pump (GEHP) is a high performance and environment-friendly equipment that can provide heating or cooling, but at present the study on the GEHP is insufficient in China. To accelerate the process of research and develop in China, this paper conducted a theoretical and experimental investigation on the GEHP. The main contents of this paper are as follows:The GEHP test-bed was reconstructed, and its detailed performances were tested. An integrated mathematic model of gas engine driven water-to-water heat pump was established according to this test-bed, and a simulation program was developed accordingly. In comparison with experiment results, the simulation errors of main performance parameters were proved to be within 10%. Using the simulation program, the performances of the GEHP in standard conditions and variable conditions were calculated. The results indicate that the primary energy ratio (PER) of the GEHP is obviously higher than other conventional heating and cooling equipments, and the part load performance of the GEHP is excellent. Optimum matching of the evaporator, condenser and compressor was studied. The affect of the total heat transfer area of the evaporator and condenser and the area ratio between them to the unit's performance were analyzed. The method to determine the total area and area ratio was put forward. The optimum matching theory and method between the gas engine and the condensing unit was established, and the fundamental principles of economic match and dynamic match were put forward. At the same time the method to analyze the economic and dynamic performance of the GEHP with engine universal characteristic curve, GEHP power balance figure, torque-conditions figure, and application range figure were illustrated. The simulation for the exhaust gas heat exchanger indicates that the character of unsteady gas flow is obvious. So it is concluded that the dynamic method should be used in designing and simulating the exhaust gas heat exchanger. Using the software package developed in this work for optimal choice of alternative refrigerants, some possible environmentally friendly alternative refrigerants for GEHP were selected, and their performances used in GEHP were simulated. The feasibility of Some HCs, HFCs and their azeotropic mixtures used by the GEHP are analyzed theoretically. Two sorts of combined absorption/compression refrigeration cycles driven by a gas engine were discussed in the last chapter. An optimal mathematical model with an objective function of PER was put forward. Using this model, the heat exchange area for each heat exchanger can be assigned properly according to the given external situation.Optimum matching of the GEHP is main study object of this paper with the experiment and computer simulation as main tools. The methods and conclusions may be helpful for the investigation and design of the GEHP.