Applicability Of Ground Source Heat Pump In Drying

Nowadays,the energy problem is serious,and the drying industry consumes a lot of energy.In order to find a way to reduce the energy consumption of drying,ground source heat pump is applied in drying.From two aspects of heat pump drying heating capacity and dehumidification capacity,double evaporator ground source heat pump drying system and open circuit ground source heat pump drying system are designed.The theoretical calculation and analysis of the two systems are carried out by using MATLAB software.It is found that the drying performance of open circuit ground source heat pump drying system is better than that of double evaporator ground source heat pump drying system.The COPs and SMER of open circuit ground source heat pump drying system increase with the increase of ambient temperature,and decrease with the increase of ambient relative humidity and set drying air temperature.TRNSYS software is used to simulate and compare the open circuit ground source heat pump drying system and the traditional closed air source heat pump drying system.The drying conditions are as follows: a.set the air supply temperature of the drying chamber as 323.15 K and the air supply volume as 1000 kg / h;b.set the air supply temperature of the drying chamber as 333.15 K and the air supply volume as 1000 kg / h.The evaporation rate of water in the drying chamber of two systems under two drying conditions was calculated,and the heat demand per hour,the power of electric auxiliary heater and the number of buried pipes were calculated.Meteonorm software was used to determine the annual meteorological data of Tianjin,and TRNSYS software was used to simulate the operation of the two systems throughout the year.The changes and differences of system heat production,auxiliary electric heater heat production,system power consumption,heat pump heating coefficient COP,system heating coefficient COPs and system dehumidification amount per unit of energy consumption SMER were compared between the two systems in two conditions.The results are as follows:(1)Under two working conditions,the monthly average system heat production,auxiliary electric heater heat production and system power consumption of the open-circuit ground source heat pump drying system are far greater than that of the closed air source heat pump drying system,which is not obvious only in June,July and August in summer.(2)open type ground source heat pump drying system and the closed air source heat pump drying system with the average COP of heat pump heating coefficient and energy consumption of dehumidification system unit SMER strength related to month,COP value of the former is lower than the latter in 6,7,8 months,the rest of the month is higher than its,SMER value is lower than the latter,by December 1,2,the rest of the month are higher than it,The monthly average system heating coefficient COPs of the open circuit ground source heat pump drying system is lower than that of the closed air source heat pump drying system throughout the year.(3)relative to the enclosed air source heat pump drying system,the open type of ground source heat pump drying system larger dehumidifying ability to change throughout the year,is mainly influenced by the environment temperature and humidity,set dry air supply temperature of 323.5K,the open type ground source heat pump drying system unit energy consumption of dehumidification quantity SMER highest and lowest value were 2.15 and 0.84,When the drying air supply temperature was set at 333.15 K,the maximum and minimum values of SMER of the open circuit ground source heat pump drying system were 1.85 and 0.79,respectively.When the drying air supply temperature was set from 323.15 K to 333.15 K,SMER value of the open circuit ground source heat pump drying system increased slightly in summer.In addition,the system heating coefficient COPs and the system dehumidification per unit energy consumption SMER of the two systems both decreased.In conclusion,compared with the closed air source heat pump drying system,the open circuit ground source heat pump drying system has stronger dehumidification capacity,but it is greatly affected by the external environment temperature and humidity.The SMER value of unit energy consumption in each month of a year changes greatly,which is lower than that of the closed air source heat pump drying system in winter.And the change trend of SMER value of open circuit ground source heat pump drying system with the set drying air temperature is also related to the season.If the industrial investment is not considered and the energy consumption is only considered,the open circuit ground source heat pump drying system is suitable for other months of the year except winter,and it is suitable for dry areas with cold winter and hot summer and rich shallow geothermal energy.