steady state simulation, advanced vapor compression systems, multiple air and refrigerant loops
The use of heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems is always increasing. This is because the HVACR systems are necessary for food production and ability to inhabit buildings that otherwise would be inhabitable. Thus, there is continued research focused on improving the efficiency and reducing the negative environmental impact of these systems. The basic vapor compression cycle (i.e., evaporator, condenser, expansion device and compressor), which is still the main underlying HVAC&R technology worldwide, has already reached its limits and researchers are investigating more creative and complex cycles to improve capacity and efficiency. This motivates the development of an enhanced general vapor compression system steady state solver. Steady state simulations require less time than transient simulations, and are used in system design optimization and cost minimization for given performance. This paper presents a comprehensive vapor compression system steady state solver which has several novel features compared to the existing solvers. Firstly, this proposed solver is capable of simulating large number of different designs of vapor compression systems. This includes arbitrary system configurations, multiple air and refrigerant paths, and user defined refrigerants. The solver uses a component-based solution scheme in which the component models are treated as black box objects. This allows a system engineer to quickly assemble and simulate a system where in the component models and performance data comes from disparate sources. This allows different vapor compression systems design engineers, and manufacturers to use the solver without the need to expose any possible confidential component data. The solver is validated using a vapor injection heat pump system with a flash tank and the preliminary modeling results match the experimental results within 10% accuracy. This heat pump system model is also tuned in order to improve the validation accuracy. A parametric case study for a variable refrigerant flow (VRF) system is presented as well to demonstrate the applicability to larger systems.