This work contributes to the improvement of energy-saving in air conditioning systems. The objective is to apply the thermal efficiency of heat exchangers for localized determination of the thermal performance of heat...This work contributes to the improvement of energy-saving in air conditioning systems. The objective is to apply the thermal efficiency of heat exchangers for localized determination of the thermal performance of heat exchangers with individually finned heat pipes. The fundamental parameters used for performance analysis were the number of fins per heat pipe, the number of heat pipes, the inlet temperatures, and the flow rates of hot and cold fluids. The heat exchanger under analysis uses Freon 404A as a working fluid in an air conditioning system for cooling in the Evaporator and energy recovery in the Condenser. The theoretical model is localized and applied individually to the Evaporator, Condenser, and heat exchanger regions. The results obtained through the simulation are compared with experimental results that use a global approach for the heat exchanger. The thermal quantities obtained through the theoretical model in the mentioned regions are air velocity, Nusselt number, thermal effectiveness, heat transfer rate, and outlet temperature. The comparisons made with global experimental results are in excellent agreement, demonstrating that the localized theoretical approach developed is consistent and can be used as a comprehensive analysis tool for heat exchangers using heat pipes.展开更多
This work contributes to the improvement of energy-saving in air conditioning systems. The objective is to apply the thermal efficiency of heat exchangers for localized determination of the thermal performance of heat...This work contributes to the improvement of energy-saving in air conditioning systems. The objective is to apply the thermal efficiency of heat exchangers for localized determination of the thermal performance of heat exchangers with individually finned heat pipes. The fundamental parameters used for performance analysis were the number of fins per heat pipe, the number of heat pipes, the inlet temperatures, and the flow rates of hot and cold fluids. The heat exchanger under analysis uses Freon 404A as a working fluid in an air conditioning system for cooling in the Evaporator and energy recovery in the Condenser. The theoretical model is localized and applied individually to the Evaporator, Condenser, and heat exchanger regions. The results obtained through the simulation are compared with experimental results that use a global approach for the heat exchanger. The thermal quantities obtained through the theoretical model in the mentioned regions are air velocity, Nusselt number, thermal effectiveness, heat transfer rate, and outlet temperature. The comparisons made with global experimental results are in excellent agreement, demonstrating that the localized theoretical approach developed is consistent and can be used as a comprehensive analysis tool for heat exchangers using heat pipes.展开更多
In order to reduce the fresh-air handing energy consumption,a fresh-air handing device using earth energy was presented. The major part is a double pipe soil-air heat exchanger. Its performance was tested in summer an...In order to reduce the fresh-air handing energy consumption,a fresh-air handing device using earth energy was presented. The major part is a double pipe soil-air heat exchanger. Its performance was tested in summer and winter. The results show that while the volume of the treated fresh-air is 125 m3/h,in summer,at the outlet of the device,the air temperature is 21.5-24.0 ℃,the air humidity ratio is about 17 g/kg,the greatest temperature drop is about 9 ℃ ,and the largest dehydration quantity is about 6 g/kg. In winter,at the outlet of the device,the air temperature is 15-17 ℃,the air humidity ratio is about 11 g/kg,the largest temperature rise is about 11 ℃,and the largest humidification quantity is about 6 g/kg. Therefore,the application of this new fresh-air handing device can take full advantage of the natural energy,thus effectively reduce the traditional energy consumption for fresh-air handing.展开更多
文摘This work contributes to the improvement of energy-saving in air conditioning systems. The objective is to apply the thermal efficiency of heat exchangers for localized determination of the thermal performance of heat exchangers with individually finned heat pipes. The fundamental parameters used for performance analysis were the number of fins per heat pipe, the number of heat pipes, the inlet temperatures, and the flow rates of hot and cold fluids. The heat exchanger under analysis uses Freon 404A as a working fluid in an air conditioning system for cooling in the Evaporator and energy recovery in the Condenser. The theoretical model is localized and applied individually to the Evaporator, Condenser, and heat exchanger regions. The results obtained through the simulation are compared with experimental results that use a global approach for the heat exchanger. The thermal quantities obtained through the theoretical model in the mentioned regions are air velocity, Nusselt number, thermal effectiveness, heat transfer rate, and outlet temperature. The comparisons made with global experimental results are in excellent agreement, demonstrating that the localized theoretical approach developed is consistent and can be used as a comprehensive analysis tool for heat exchangers using heat pipes.
文摘This work contributes to the improvement of energy-saving in air conditioning systems. The objective is to apply the thermal efficiency of heat exchangers for localized determination of the thermal performance of heat exchangers with individually finned heat pipes. The fundamental parameters used for performance analysis were the number of fins per heat pipe, the number of heat pipes, the inlet temperatures, and the flow rates of hot and cold fluids. The heat exchanger under analysis uses Freon 404A as a working fluid in an air conditioning system for cooling in the Evaporator and energy recovery in the Condenser. The theoretical model is localized and applied individually to the Evaporator, Condenser, and heat exchanger regions. The results obtained through the simulation are compared with experimental results that use a global approach for the heat exchanger. The thermal quantities obtained through the theoretical model in the mentioned regions are air velocity, Nusselt number, thermal effectiveness, heat transfer rate, and outlet temperature. The comparisons made with global experimental results are in excellent agreement, demonstrating that the localized theoretical approach developed is consistent and can be used as a comprehensive analysis tool for heat exchangers using heat pipes.
基金Project(2006BAJ01A02) supported by the Chinese of Science and Technology during the 11th Five-Year Plan Period
文摘In order to reduce the fresh-air handing energy consumption,a fresh-air handing device using earth energy was presented. The major part is a double pipe soil-air heat exchanger. Its performance was tested in summer and winter. The results show that while the volume of the treated fresh-air is 125 m3/h,in summer,at the outlet of the device,the air temperature is 21.5-24.0 ℃,the air humidity ratio is about 17 g/kg,the greatest temperature drop is about 9 ℃ ,and the largest dehydration quantity is about 6 g/kg. In winter,at the outlet of the device,the air temperature is 15-17 ℃,the air humidity ratio is about 11 g/kg,the largest temperature rise is about 11 ℃,and the largest humidification quantity is about 6 g/kg. Therefore,the application of this new fresh-air handing device can take full advantage of the natural energy,thus effectively reduce the traditional energy consumption for fresh-air handing.
