Currently,people pay more and more attention to the transitional resettlement of victims after various natural disasters.There is an urgent need for a large number of temporary houses to resettle the victims after nat...Currently,people pay more and more attention to the transitional resettlement of victims after various natural disasters.There is an urgent need for a large number of temporary houses to resettle the victims after natural disasters.Disaster-relief temporary houses(DTHs)played an important role in the post-disaster resettlement in the past,which can not only be produced on a large scale,but also can be quickly and conveniently erected,which were the main means to solve the problem of transitional resettlement.However,due to their temporary nature,there was no extra energy consuming system installed in the DTHs generally.Hence the indoor thermal environment inside the DTHs was severe in summer.In this study,combined with the field experimental tests of the DTHs in Wenchuan Earthquake and Lushan Earthquake and the experimental study of the full-size DTH,it found that the thermal environment inside the DTH was intolerably high in summer.It had negative impact on victims.In order to improve the thermal environment inside DTHs during post-disaster period which lacked of extra energy resources,this study used the method of combining phase change materials(PCMs)with walls of the DTH to explore its feasibility and effectiveness.The results showed that PCMs could effectively improve the thermal environment inside the DTH in summer.Furthermore,the difference of the composite positions between PCMs and the wall affected the improvement effect.The energy release rate of the PCMs assembly system(PAS)varied according to the positions of the PCMs.展开更多
Refrigeration systems are essential across various sectors,including food preservation,medical storage,and climate control.However,their high energy consumption and environmental impact necessitate innovative solution...Refrigeration systems are essential across various sectors,including food preservation,medical storage,and climate control.However,their high energy consumption and environmental impact necessitate innovative solutions to enhance efficiency while minimizing energy usage.This paper investigates the integration of Phase Change Materials(PCMs)into a vapor compression refrigeration system to enhance energy efficiency and temperature regulation for food preservation.A multifunctional prototype was tested under two configurations:(1)a standard thermally insulated room,and(2)the same room augmented with eutectic plates filled with either Glaceol(-10℃ melting point)or distilled water(0℃ melting point).Thermocouples were calibrated and deployed to record air and PCM temperatures during freeze–thaw cycles at thermostat setpoints of and Additionally,a-30℃ -35℃ .defrosting resistor and timer were added to mitigate frost buildup,a known cause of efficiency loss.The experimental results show that PCM-enhanced rooms achieved up to 10.98℃ greater temperature stability during defrost cycles and reduced energy consumption by as much as 7.76%(from 0.4584 to 0.4231 kWh/h).Moreover,the effectiveness of PCMs depended strongly on thermostat settings and PCM type,with distilled water demonstrating broader solidification across plates under higher ambient loads.These findings highlight the potential of PCM integration to improve cold-chain performance,offering rapid cooling,moisture retention,and extended product conservation during power interruptions.展开更多
This work investigates the transient behaviour of a phase change material based cool thermal energy storage (CTES) system comprised of a cylindrical storage tank filled with encapsulated phase change materials (PCMs) ...This work investigates the transient behaviour of a phase change material based cool thermal energy storage (CTES) system comprised of a cylindrical storage tank filled with encapsulated phase change materials (PCMs) in spherical container integrated with an ethylene glycol chiller plant. A simulation program was developed to evaluate the temperature histories of the heat transfer fluid (HTF) and the phase change material at any axial location during the charging period. The results of the model were validated by comparison with experimental results of temperature profiles of HTF and PCM. The model was also used to investigate the effect of porosity, Stanton number, Stefan number and Peclet number on CTES system performance. The results showed that increase in porosity contributes to a higher rate of energy storage. However, for a given geometry and heat transfer coefficient, the mass of PCM charged in the unit decreases as the increase in porosity. The St number as well as the Ste number is also influential in the performance of the unit. The model is a convenient and more suitable method to determine the heat transfer characteristics of CTES system. The results reported are much useful for designing CTES system.展开更多
Paraffin wax is a perfect phase change material(PCM)that can be used in latent heat storage units(LHSUs).The utilization of such LHSU is restricted by the poor conductivity of PCM.In the present work,a metal foam made...Paraffin wax is a perfect phase change material(PCM)that can be used in latent heat storage units(LHSUs).The utilization of such LHSU is restricted by the poor conductivity of PCM.In the present work,a metal foam made of aluminium with PCM was used to produce a composite PCM as a thermal conductivity technique in PCM⁃LHSU and water was used as heat transfer fluid(HTF).An experimental investigation was carried out to evaluate the heat transfer characteristics of LHSU using pure PCM and composite PCM.The study included time⁃dependent visualization of the PCM during the melting and solidification processes.Besides,a thermocouple network was placed inside the heat storage to record the temperature profile during each process.Results showed that better performance could be obtained using composite PCM⁃LHSU for both melting and solidification processes.The melting time of composite PCM⁃LHSU was about 83%faster than that of a simple PCM⁃LHSU,and the percentage decreasing in the solidification time was about 85%due to the provision of metal foam.展开更多
In thermal systems such as solar thermal and waste heat recovery systems, the available energy supply does not usually coincide in time with the process demand. Hence some form of thermal energy storage (TES) is neces...In thermal systems such as solar thermal and waste heat recovery systems, the available energy supply does not usually coincide in time with the process demand. Hence some form of thermal energy storage (TES) is necessary for the most effective utilization of the energy source. This study deals with the experimental evaluation of thermal performance of a packed bed latent heat TES unit integrated with solar flat plate collector. The TES unit contains paraffin as phase change material (PCM) filled in spherical capsules, which are packed in an insulated cylindrical storage tank. The water used as heat transfer fluid (HTF) to transfer heat from the solar collector to the storage tank also acts as sensible heat storage material. Charging experiments were carried out at varying inlet fluid temperatures to examine the effects of porosity and HTF flow rate on the storage unit performance. The performance parameters such as instantaneous heat stored, cumulative heat stored, charging rate and system efficiency are studied. Discharging experiments were carried out by both continuous and batchwise processes to recover the stored heat, and the results are presented.展开更多
The usage of phase change materials (PCM) to store the heat in the form of latent heat is increased, because large quantity of thermal energy is stored in smaller volumes. In the present experimental investigation, so...The usage of phase change materials (PCM) to store the heat in the form of latent heat is increased, because large quantity of thermal energy is stored in smaller volumes. In the present experimental investigation, sodium thiosulphate pentahydrate is employed as phase change material and it is stored in stainless steel capsules. These capsules are kept in fabricated tank and hot water is supplied into it. The experimental design is prepared by considering the parameters: flow rate, heat transfer fluid inlet temperature and PCM capsule shape. Experiments are conducted according to the experimental design and responses are recorded. The effect of selected parameters on TES using PCM is studied by analyzing experimental data. The experimental data are also analyzed using Fuzzy Logic to find the optimal values of flow rate, heat transfer fluid inlet temperature and PCM capsule shapes. The present work utilizes Fuzzy Logic to find the optimal parameters for designing the effective Thermal Energy Storage System (TES).展开更多
Presents the application of such components as MT8980 and MT8924 in digital switch modules for trunking system, and design and implementation of digital switch modules, which can perform the functions of digital switc...Presents the application of such components as MT8980 and MT8924 in digital switch modules for trunking system, and design and implementation of digital switch modules, which can perform the functions of digital switch and conference call, and replace analog switch modules and maintain compatibility with analog systems so that the system can gradually and continuously updated to full digitization.展开更多
文摘Currently,people pay more and more attention to the transitional resettlement of victims after various natural disasters.There is an urgent need for a large number of temporary houses to resettle the victims after natural disasters.Disaster-relief temporary houses(DTHs)played an important role in the post-disaster resettlement in the past,which can not only be produced on a large scale,but also can be quickly and conveniently erected,which were the main means to solve the problem of transitional resettlement.However,due to their temporary nature,there was no extra energy consuming system installed in the DTHs generally.Hence the indoor thermal environment inside the DTHs was severe in summer.In this study,combined with the field experimental tests of the DTHs in Wenchuan Earthquake and Lushan Earthquake and the experimental study of the full-size DTH,it found that the thermal environment inside the DTH was intolerably high in summer.It had negative impact on victims.In order to improve the thermal environment inside DTHs during post-disaster period which lacked of extra energy resources,this study used the method of combining phase change materials(PCMs)with walls of the DTH to explore its feasibility and effectiveness.The results showed that PCMs could effectively improve the thermal environment inside the DTH in summer.Furthermore,the difference of the composite positions between PCMs and the wall affected the improvement effect.The energy release rate of the PCMs assembly system(PAS)varied according to the positions of the PCMs.
基金supported in entire part by the Biomaterials and Transport Phenomena Laboratory Agreement No.30303-12-2003,at the University of Medea.
文摘Refrigeration systems are essential across various sectors,including food preservation,medical storage,and climate control.However,their high energy consumption and environmental impact necessitate innovative solutions to enhance efficiency while minimizing energy usage.This paper investigates the integration of Phase Change Materials(PCMs)into a vapor compression refrigeration system to enhance energy efficiency and temperature regulation for food preservation.A multifunctional prototype was tested under two configurations:(1)a standard thermally insulated room,and(2)the same room augmented with eutectic plates filled with either Glaceol(-10℃ melting point)or distilled water(0℃ melting point).Thermocouples were calibrated and deployed to record air and PCM temperatures during freeze–thaw cycles at thermostat setpoints of and Additionally,a-30℃ -35℃ .defrosting resistor and timer were added to mitigate frost buildup,a known cause of efficiency loss.The experimental results show that PCM-enhanced rooms achieved up to 10.98℃ greater temperature stability during defrost cycles and reduced energy consumption by as much as 7.76%(from 0.4584 to 0.4231 kWh/h).Moreover,the effectiveness of PCMs depended strongly on thermostat settings and PCM type,with distilled water demonstrating broader solidification across plates under higher ambient loads.These findings highlight the potential of PCM integration to improve cold-chain performance,offering rapid cooling,moisture retention,and extended product conservation during power interruptions.
文摘This work investigates the transient behaviour of a phase change material based cool thermal energy storage (CTES) system comprised of a cylindrical storage tank filled with encapsulated phase change materials (PCMs) in spherical container integrated with an ethylene glycol chiller plant. A simulation program was developed to evaluate the temperature histories of the heat transfer fluid (HTF) and the phase change material at any axial location during the charging period. The results of the model were validated by comparison with experimental results of temperature profiles of HTF and PCM. The model was also used to investigate the effect of porosity, Stanton number, Stefan number and Peclet number on CTES system performance. The results showed that increase in porosity contributes to a higher rate of energy storage. However, for a given geometry and heat transfer coefficient, the mass of PCM charged in the unit decreases as the increase in porosity. The St number as well as the Ste number is also influential in the performance of the unit. The model is a convenient and more suitable method to determine the heat transfer characteristics of CTES system. The results reported are much useful for designing CTES system.
文摘Paraffin wax is a perfect phase change material(PCM)that can be used in latent heat storage units(LHSUs).The utilization of such LHSU is restricted by the poor conductivity of PCM.In the present work,a metal foam made of aluminium with PCM was used to produce a composite PCM as a thermal conductivity technique in PCM⁃LHSU and water was used as heat transfer fluid(HTF).An experimental investigation was carried out to evaluate the heat transfer characteristics of LHSU using pure PCM and composite PCM.The study included time⁃dependent visualization of the PCM during the melting and solidification processes.Besides,a thermocouple network was placed inside the heat storage to record the temperature profile during each process.Results showed that better performance could be obtained using composite PCM⁃LHSU for both melting and solidification processes.The melting time of composite PCM⁃LHSU was about 83%faster than that of a simple PCM⁃LHSU,and the percentage decreasing in the solidification time was about 85%due to the provision of metal foam.
基金Project supported by Sri Venkateswara college of Engineering,India.
文摘In thermal systems such as solar thermal and waste heat recovery systems, the available energy supply does not usually coincide in time with the process demand. Hence some form of thermal energy storage (TES) is necessary for the most effective utilization of the energy source. This study deals with the experimental evaluation of thermal performance of a packed bed latent heat TES unit integrated with solar flat plate collector. The TES unit contains paraffin as phase change material (PCM) filled in spherical capsules, which are packed in an insulated cylindrical storage tank. The water used as heat transfer fluid (HTF) to transfer heat from the solar collector to the storage tank also acts as sensible heat storage material. Charging experiments were carried out at varying inlet fluid temperatures to examine the effects of porosity and HTF flow rate on the storage unit performance. The performance parameters such as instantaneous heat stored, cumulative heat stored, charging rate and system efficiency are studied. Discharging experiments were carried out by both continuous and batchwise processes to recover the stored heat, and the results are presented.
文摘The usage of phase change materials (PCM) to store the heat in the form of latent heat is increased, because large quantity of thermal energy is stored in smaller volumes. In the present experimental investigation, sodium thiosulphate pentahydrate is employed as phase change material and it is stored in stainless steel capsules. These capsules are kept in fabricated tank and hot water is supplied into it. The experimental design is prepared by considering the parameters: flow rate, heat transfer fluid inlet temperature and PCM capsule shape. Experiments are conducted according to the experimental design and responses are recorded. The effect of selected parameters on TES using PCM is studied by analyzing experimental data. The experimental data are also analyzed using Fuzzy Logic to find the optimal values of flow rate, heat transfer fluid inlet temperature and PCM capsule shapes. The present work utilizes Fuzzy Logic to find the optimal parameters for designing the effective Thermal Energy Storage System (TES).
文摘Presents the application of such components as MT8980 and MT8924 in digital switch modules for trunking system, and design and implementation of digital switch modules, which can perform the functions of digital switch and conference call, and replace analog switch modules and maintain compatibility with analog systems so that the system can gradually and continuously updated to full digitization.
