Simulation Research Of High Temperature Heat Pump System Based On Waste Heat Utilization

The industrial sector is one of the top three energy consumption sectors in the world.20-50% of the energy consumed in the industrial manufacturing process is lost in the form of waste heat.As a large manufacturing country,China has a huge amount of low-temperature waste heat emissions,if waste heat recovery technology is used reasonably,it will make a great contribution to energy conservation and emission reduction.High temperature pump has attracted much attention due to its efficient energy saving technology which can convert low energy into high energy.Industrial application needs higher pump output temperature,however,present researches of high temperature pump mainly focus on 60-90? application.Lower heating temperature limits present high temperature pump applicate and popularize.This paper proposed a high temperature heat pump system which can reach 120? heating temperature to satisfy 100? heating temperature needs.The research included three aspects: high temperature working fluid selection,high temperature heat pump equipment selection and system design calculation,mathematical model and system simulation.In high temperature working fluid selection,theoretical cycle was calculated by MATLAB and REFPROP to select suitable high temperature heat pump working fluid.The results showed that R152 a and R134 a were suitable for working conditions below 80?.R1234 a was best on 80-100? condition,If condensation temperature was above 100?,R245 fa was suitable high temperature heat pump working fluid,but heat production per unit volume is low.In the section of high-temperature heat pump equipment selection and system design and calculation,this paper selects compressors and expansion valves suitable for hightemperature working fluids according to the operating characteristics of high-temperature heat pumps,and designs and calculates heat exchangers.In the establishment of the mathematical model and the system simulation part,this paper establishes the steady state simulation mathematical model of the four major parts of the high temperature heat pump by using the efficiency method of the compressor and the partition calculation method of the condenser and the evaporator.Using the EES equation solver,the heating capacity of the heat pump system,the compressor input power,and the coefficient of performance COP are simulated and calculated.The results show that the unit is condensed at 120? and the COP at 45? temperature rise is 4.32,the heating capacity reached 201.1k W.The effects of subcooling and superheat changes on the system cycle were calculated.The results show that: when the supercooling degree increases from 2? to 10?,the heating capacity of the system increases by 17.1%,the input power of the compressor increases by 10.3%,COP The value is increased by 8.9%;the superheat is reduced from 10? to 2?,the system heating capacity is increased by 14.7%,the compressor input power is increased by 7.2%,and the COP is increased by 11.5%.Increasing the liquid supercooling degree and reducing the evaporator outlet superheat degree can effectively improve the system performance coefficient.