The relationship among the hydrogen storage properties, cycling characteristics and thermal parameters of the metal hydride air conditioning systems was investigated. Based on a new alloy selection model, three pairs ...The relationship among the hydrogen storage properties, cycling characteristics and thermal parameters of the metal hydride air conditioning systems was investigated. Based on a new alloy selection model, three pairs of hydrogen storage alloys, LaNi_ 4.4 Mn_ 0.26 Al_ 0.34 / La_ 0.6 Nd_ 0.4 Ni_ 4.8 Mn_ 0.2 Cu_ 0.1 ,LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Nd_ 0.4 Ni_ 4.8 Mn_ 0.2 Cu_ 0.1 and LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Y_ 0.4 Ni_ 4.8 Mn_ 0.2 , were selected as the working materials for the metal hydride air conditioning system. Studies on the factors affecting the COP of the system showed that higher COP and available hydrogen content need the proper operating temperature and cycling time,large hydrogen storage capacity, flat plateau and small hysterisis of hydrogen alloys, proper original input hydrogen content and mass ratio of the pair of alloys. It also needs small weight, heat capacity and good heat conductivity of the reaction beds. An experimental metal hydride air-conditioning system was established by using LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Y_ 0.4 Ni_ 4.8 Mn_ 0.2 alloys as the working materials, which showed that under the operating temperature of 180℃/40℃, a low temperature of 13℃ was reached, with COP =0.38 and W_ net =0.09 kW/kg.展开更多
In this study,the potential implementation of three different low-GWP refrigerants(R32,R452B,and R454B)as replacements for R410A was investigated.The study was performed using a simulation tool developed by the author...In this study,the potential implementation of three different low-GWP refrigerants(R32,R452B,and R454B)as replacements for R410A was investigated.The study was performed using a simulation tool developed by the authors called RACHP-Lab,which is a vapor compression system simulation tool developed based on physics-based simulation for typical mini-split air conditioners.The simulation study was carried out and validated using experimental performance data of 10 different air conditioning units available in the Egyptian market.The units included fixed-speed or variable-speed compressors and operated in cooling or heating modes.Drop-in replace-ment with the new refrigerants was carried out.For R32,the capacity increased between 4.9%and 13%for cooling cases,and 6.3%and 12.4%for heating cases.However,COP did not improve in all cases.For R452B and R454B with direct replacement,the capacity nearly remained the same,with an increase of COP between 1.6%and 8.0%.Soft optimization was also conducted on cooling cases where compressor suction superheat,condenser subcooling,and compressor volumetric speed were optimized to maximize COP while maintaining the original capacity of R410A.R32 showed an improvement of COP over R410A between 4.6%and 15.5%,while for R452B and R454B between 2.2%and 13.2%.展开更多
基金The Natural Science Foundation of China (50266063) .
文摘The relationship among the hydrogen storage properties, cycling characteristics and thermal parameters of the metal hydride air conditioning systems was investigated. Based on a new alloy selection model, three pairs of hydrogen storage alloys, LaNi_ 4.4 Mn_ 0.26 Al_ 0.34 / La_ 0.6 Nd_ 0.4 Ni_ 4.8 Mn_ 0.2 Cu_ 0.1 ,LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Nd_ 0.4 Ni_ 4.8 Mn_ 0.2 Cu_ 0.1 and LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Y_ 0.4 Ni_ 4.8 Mn_ 0.2 , were selected as the working materials for the metal hydride air conditioning system. Studies on the factors affecting the COP of the system showed that higher COP and available hydrogen content need the proper operating temperature and cycling time,large hydrogen storage capacity, flat plateau and small hysterisis of hydrogen alloys, proper original input hydrogen content and mass ratio of the pair of alloys. It also needs small weight, heat capacity and good heat conductivity of the reaction beds. An experimental metal hydride air-conditioning system was established by using LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Y_ 0.4 Ni_ 4.8 Mn_ 0.2 alloys as the working materials, which showed that under the operating temperature of 180℃/40℃, a low temperature of 13℃ was reached, with COP =0.38 and W_ net =0.09 kW/kg.
文摘In this study,the potential implementation of three different low-GWP refrigerants(R32,R452B,and R454B)as replacements for R410A was investigated.The study was performed using a simulation tool developed by the authors called RACHP-Lab,which is a vapor compression system simulation tool developed based on physics-based simulation for typical mini-split air conditioners.The simulation study was carried out and validated using experimental performance data of 10 different air conditioning units available in the Egyptian market.The units included fixed-speed or variable-speed compressors and operated in cooling or heating modes.Drop-in replace-ment with the new refrigerants was carried out.For R32,the capacity increased between 4.9%and 13%for cooling cases,and 6.3%and 12.4%for heating cases.However,COP did not improve in all cases.For R452B and R454B with direct replacement,the capacity nearly remained the same,with an increase of COP between 1.6%and 8.0%.Soft optimization was also conducted on cooling cases where compressor suction superheat,condenser subcooling,and compressor volumetric speed were optimized to maximize COP while maintaining the original capacity of R410A.R32 showed an improvement of COP over R410A between 4.6%and 15.5%,while for R452B and R454B between 2.2%and 13.2%.
