Comparison of a dynamic simulation and experiments on a gas-fired water pump system.

摘要

A gas-fired water pump system has been set up and tested at The Ohio State University. This system contains a piston-cylinder power unit, a vapor generator, a condenser, a recuperative heat exchanger, a condensate pump, and a water pumping unit. Refrigerant 113 is used as the working medium in the system. Propane gas is used as the energy source in the vapor generator. Water is used as the coolant in the condenser. In the power and water pumping units, a frictionless rolling diaphragm piston cylinder unit is used.; A lumped parameter model has been developed to study the dynamic performance of the system. Thermodynamic and Kinematic equations are coupled together to predict the thermodynamic state of the working medium inside the three major components: the top hat pressure tank, the power chamber, and the transfer case. The operation speed predicted by the simulation was within 13% of the results obtained from the tests.; Parametric analysis based on the simulation model was done to investigate the effects of seven operating conditions on the system performance. These include four geometrical parameters: stroke length, piston diameter, orifice size, and pivot ratio. The operating parameters used in the analysis are vapor generator pressure, condenser pressure, and water pump vacuum. It is concluded on the basis of such an analysis that the system should be run at a lower water pump vacuum because a higher vacuum does not contribute to improving the system performance; instead a lot of energy is wasted in pumping against vacuum. The stroke length and the piston diameter can be optimized based on the actual operating conditions. A valve which does not restrict the flow should be used in the system.; The rolling diaphragm piston cylinder unit can be suitably modified to be used as a motor compressor in a heat pump system. This model can also be modified to simulate one such component before it is built. The simulation model provides a way to optimize the current system based on the real operating conditions, thus enabling the design of a new better system.