Simulation And Experimental Research On Cold Water Phase Change Energy Heat Pump System

Using water source heat pump system to supply heat and cooling for buildings has huge energy saving and emission reduction benefits,and it is an important way to alleviate energy consumption and environmental pollution of HVAC.However,there are two bottlenecks in the development and application of the heat pump system:low water temperature in winter and less water resources.Therefore,the idea of breaking through the freezing point and exploiting the condensed solid phase transformation energy released by the freezing of cold water as the heat source of the heat pump system is put forward.This paper focuses on the system form,operation characteristics and energy consumption characteristics of cold-water phase-change energy heat pump.The main research contents and results are as follows:(1)Compared with the conventional water source heat pump system,the cold water phase energy heat pump system has lower water temperature,which leads to the decrease of energy efficiency ratio of heat pump units.In order to study whether the heat pump system can save energy under the condition of cold-water phase-change energy heat pump system,the simulation system of heat pump unit is established by using simulink,and the mathematical models of compressor,condenser,throttle valve and evaporator are constructed.The variation law of energy efficiency ratio of heat pump unit under different conditions is simulated and studied,which provides theoretical guidance for experiment.The simulation results show that the heat pump system still has good energy-saving performance under the cold-water phase change condition.(2)The key technical problem of cold-water phase-change energy heat pump system is how to realize the uninterrupted cycle of heating and freezing,rapid de-icing and re-icing of the system.A method of de-icing combining intermittent thermal melting and mechanical de-icing is proposed.SolidWorks three-dimensional modeling is used to illustrate the process structure of the cold-water phase change machine.The system composition,principle and design operating conditions are introduced in detail.How to realize the continuous cycle of ice-freezing,ice-melting and ice-recrystallization is explained.(3)Build an experimental system to further study the operating characteristics and energy consumption characteristics of the system.The experimental results show that the system is stable in operation.During the hot icing process,the thickness of the ice layer is about 7mm~8mm thick.The experimental calculation shows that the heat transfer coefficient K of the cold water phase change machine is about 0.52 W/(m~2·K),and the deicing energy consumption accounts for about 13.3%of the total system heat.Experimental studies have found that the energy efficiency ratio of the cold water phase change energy heat pump system fluctuates around 3.The experimental and simulation values are compared and analyzed.The experimental values agree well with the simulated values within the error acceptance range.(4)The operation effect,energy consumption and environmental benefits of the cold water phase change energy and water source coupled heat pump system were studied.The operation results show that the coupled heat pump system with surface water source and cold water phase change energy is stable,and the indoor temperature can be stably maintained at around 20°C in winter.In the coldest month of winter,the water temperature of the water source is lower than 2°C,and the energy efficiency ratio of the coupled heat pump system is about 3.In addition,the coupled heat pump system is about20%more energy efficient than the coal-fired heating system.The research of this system has important practical significance for solving the problem of limited application of water source heat pump system in cold regions of northern China..