Performance Analysis And Optimization Of Rooftop Unit

Since the rooftop unit has been widely used in china these years.The traditional manual design calculation method is inefficient with very poor accuracy.There is stilll no corresponding simulation model and software to facilitate the design and simulation calculation of the rooftop unit.Rooftop unit has higher requirements for the stability of refrigeration or heat production together with vibration noise.Therefore,based on the theory of ordinary vapor compression refrigeration,this paper establishes a design and simulation system,and designs relevant software for the design and simulation of rooftop unit.In this paper,a roof heat pump air conditioning system is designed for a certain condition,and the structure and type selection of each component are given.The simulation results are checked and calculated.Finally,the simulation results are compared with experiments to check the accuracyof the simulation system.The main research results are as follows:(1)By fitting the Refprop data source,a set of R410 A thermal physical properties and transmission characteristics calculation model is established.The relative error of the model is kept within ±10%,so the model has both high accuracy and high calculation speed.(2)A steady-state simulation model for the design of heat exchanger is established with the given design condition and heat load of the rooftop unit,and a rooftop heat pump air conditioning system with double evaporators in parallel is established according to the characteristics of the roof air conditioning system.The main components of the vapor compression refrigeration system are designed and selected.(3)According to the basic principle of the operation of each component,the simulation model of each main component is established and integrated into the steady-state simulation model of the system.The designed system is simulated and checked,and the performance of the system under multiple working conditions is calculated by the simulation model for variable conditio analysis of the model.(4)According to the result of the design,the experimental bench of roof air-conditioning system was built,and several conditions were selected to test and verify whether the designed system can meet the design requirements,also the accuracy of the simulation model was verified.(5)Based on the design and simulation above,the corresponding simulation analysis software for rooftop unit design is developed.The software can satisfy the requirements of system design and type selection function of rooftop unit,and can also output the selection results digitally.The simulation module included in the software can simulate and calculate the simulation results to verify the design.