Paraffin/γ-Al2O3 composites as phase change energy storage materials were prepared by absorbing paraffin in porous network of γ-Al2O3.In the composite materials,paraffin was used as a phase change material(PCM)for t...Paraffin/γ-Al2O3 composites as phase change energy storage materials were prepared by absorbing paraffin in porous network of γ-Al2O3.In the composite materials,paraffin was used as a phase change material(PCM)for thermal energy storage,and γ-Al2O3 acted as supporting materials.Characterizations were conducted to evaluate the energy storage performance of the composites,and differential scanning calorimeter results showed that the PCM-3 composite has melting latent heat of 112.9 kJ/kg with a melting temperature of 62.9 ℃.Due to strong capillary force and surface tension between paraffin and γ-Al2O3,the leakage of melted paraffin from the composites can be effectively prevented.Therefore,the paraffin/γ-Al2O3 composites have a good thermal stability and can be used repeatedly.展开更多
The conventional solar heating floor system contains a big water tank to store energy in the day time for heating at night,which takes much building space and is very heavy.In order to reduce the water tank volume eve...The conventional solar heating floor system contains a big water tank to store energy in the day time for heating at night,which takes much building space and is very heavy.In order to reduce the water tank volume even to cancel the tank,a novel structure of integrated water pipe floor heating system using shape-stabilized phase change materials(SSPCM)for thermal energy storage was developed.A numerical model was developed to analyze the performance of SSPCM floor heating system under the intermittent heating condition,which was verified by our experimental data.The thermal performance of the heating system and the effects of various factors on it were analyzed numerically.The factors including phase transition temperature,heat of fusion,thermal conductivity of SSPCM and thermal conductivity of the decoration material were analyzed.The results show that tm and kd are the most import influencing factors on the thermal performance of SSPCM floor heating system,since they determine the heat source temperature and thermal resistance between SSPCM plates and indoor air,respectively.Hm should be large to store enough thermal energy in the day time for nighttimes heating.The effects of kp can be ignored in this system.The SSPCM floor heating system has potential of making use of the daytime solar energy for heating at night efficiently in various climates when its structure is properly designed.展开更多
Based on the phase change material (PCM) thermal characteristic,some testing methods such as differential scanning calorimeter (DSC) etc were used to select the low melting mixture of capric and lauric acid as PCM of ...Based on the phase change material (PCM) thermal characteristic,some testing methods such as differential scanning calorimeter (DSC) etc were used to select the low melting mixture of capric and lauric acid as PCM of phase change wallboard (PCW). The PCW room was established,and some contrast analysis of the storage and exchange thermal characteristic of PCW room and ordinary wall room were made under different conditions. The results show that the fluctuation of indoor air temperature in PCW room is smaller than that in ordinary room obviously. The exchange energy of PCM room with outdoor is less than that of ordinary wall room. In the winter condition,PCW room utilizes valley period electricity to storage energy in the night,while releases at peak period electricity in daytime,which can divert 40% of peak load. In the summer condition,PCW room can reduce the peak cooling load by 25% compared with ordinary wall room.展开更多
To solve the fundamental problem of insufficient heat available during defrosting while ensuring the efficient and safe system operation for air-source heat pumps (ASHPs). A novel reverse-cycle defrosting (NRCD) metho...To solve the fundamental problem of insufficient heat available during defrosting while ensuring the efficient and safe system operation for air-source heat pumps (ASHPs). A novel reverse-cycle defrosting (NRCD) method based on thermal energy storage to eliminate frost off the outdoor coil surface was developed. Comparative experiments using both the stand reverse cycle defrosting (SRCD) method and the NRCD method were carried out on an experimental ASHP unit with a nominal 2.5 kW heating capacity. The results indicate that during defrosting operation, using the NRCD method improves discharge and suction pressures by 0.24 MPa and 0.19 MPa, respectively, shortens defrosting duration by 60%, and reduces the defrosting energy consumption by 48.1% in the experimental environment, compared with those by the use of SRCD method. Therefore, using the NRCD method can shorten the defrosting duration, improve the indoor thermal comfort, and reduce the defrosting energy consumption in defrosting.展开更多
文摘Paraffin/γ-Al2O3 composites as phase change energy storage materials were prepared by absorbing paraffin in porous network of γ-Al2O3.In the composite materials,paraffin was used as a phase change material(PCM)for thermal energy storage,and γ-Al2O3 acted as supporting materials.Characterizations were conducted to evaluate the energy storage performance of the composites,and differential scanning calorimeter results showed that the PCM-3 composite has melting latent heat of 112.9 kJ/kg with a melting temperature of 62.9 ℃.Due to strong capillary force and surface tension between paraffin and γ-Al2O3,the leakage of melted paraffin from the composites can be effectively prevented.Therefore,the paraffin/γ-Al2O3 composites have a good thermal stability and can be used repeatedly.
基金Supported by National 11th Five-Year Plan of Dept.of Science,China(2006BAA04B02,2006BAJ02A09)
文摘The conventional solar heating floor system contains a big water tank to store energy in the day time for heating at night,which takes much building space and is very heavy.In order to reduce the water tank volume even to cancel the tank,a novel structure of integrated water pipe floor heating system using shape-stabilized phase change materials(SSPCM)for thermal energy storage was developed.A numerical model was developed to analyze the performance of SSPCM floor heating system under the intermittent heating condition,which was verified by our experimental data.The thermal performance of the heating system and the effects of various factors on it were analyzed numerically.The factors including phase transition temperature,heat of fusion,thermal conductivity of SSPCM and thermal conductivity of the decoration material were analyzed.The results show that tm and kd are the most import influencing factors on the thermal performance of SSPCM floor heating system,since they determine the heat source temperature and thermal resistance between SSPCM plates and indoor air,respectively.Hm should be large to store enough thermal energy in the day time for nighttimes heating.The effects of kp can be ignored in this system.The SSPCM floor heating system has potential of making use of the daytime solar energy for heating at night efficiently in various climates when its structure is properly designed.
基金Project(50878133) supported by the National Natural Science Foundation of ChinaProject (2007R37) supported by Excellent Talents in Liaoning Province+1 种基金Project (2008S193) supported by the Key Laboratory Fund of Education Department in Liaoning ProvinceProject(1071211-1-00) supported by the Scientific and Technical Fund Project Subsidy of Shenyang Province
文摘Based on the phase change material (PCM) thermal characteristic,some testing methods such as differential scanning calorimeter (DSC) etc were used to select the low melting mixture of capric and lauric acid as PCM of phase change wallboard (PCW). The PCW room was established,and some contrast analysis of the storage and exchange thermal characteristic of PCW room and ordinary wall room were made under different conditions. The results show that the fluctuation of indoor air temperature in PCW room is smaller than that in ordinary room obviously. The exchange energy of PCM room with outdoor is less than that of ordinary wall room. In the winter condition,PCW room utilizes valley period electricity to storage energy in the night,while releases at peak period electricity in daytime,which can divert 40% of peak load. In the summer condition,PCW room can reduce the peak cooling load by 25% compared with ordinary wall room.
基金Project(50606007) supported by the National Natural Science Foundation of China
文摘To solve the fundamental problem of insufficient heat available during defrosting while ensuring the efficient and safe system operation for air-source heat pumps (ASHPs). A novel reverse-cycle defrosting (NRCD) method based on thermal energy storage to eliminate frost off the outdoor coil surface was developed. Comparative experiments using both the stand reverse cycle defrosting (SRCD) method and the NRCD method were carried out on an experimental ASHP unit with a nominal 2.5 kW heating capacity. The results indicate that during defrosting operation, using the NRCD method improves discharge and suction pressures by 0.24 MPa and 0.19 MPa, respectively, shortens defrosting duration by 60%, and reduces the defrosting energy consumption by 48.1% in the experimental environment, compared with those by the use of SRCD method. Therefore, using the NRCD method can shorten the defrosting duration, improve the indoor thermal comfort, and reduce the defrosting energy consumption in defrosting.
