Pub Date : 2023-01-31DOI: 10.18186/thermal.1245298
Sattar Aljabair, Israa Alesbe, S. Ibrahim
One of the appealing technologies that contributes to raising the energy storage density is latent heat thermal energy storage. The heat of fusion is isothermally stored at a temperature representing the temperature at which a phase-change material transitions between phases. The current research provides a review of how phase transition materials are used in melting and solidification. Generally, the range of working temperature extends from -20 °C to 200 °C for solidification and melting applications. The first range (-20 to 5 °C) is employed for commercial and domestic refrigeration. The second range (5 to 40 °C) is utilized to lower the energy requirements for air-conditioning applications. The applications includes in third range (40 to 82 °C) are solar collector and heating of water. Applications of absorption cooling, waste electricity generations, and heat recovery are operated at high temperature range (82 to180 °C). There are various types of PCMs for all the above temperature ranges. The present review paper will discuss the application field, Geometry, PCM type, heat transfer augmentation technique and their effects on the performance. The conclusions are mentioned to give more insight about the PCM behavior in various applications.
{"title":"Review on latent thermal energy storage using phase change material","authors":"Sattar Aljabair, Israa Alesbe, S. Ibrahim","doi":"10.18186/thermal.1245298","DOIUrl":"https://doi.org/10.18186/thermal.1245298","url":null,"abstract":"One of the appealing technologies that contributes to raising the energy storage density is latent heat thermal energy storage. The heat of fusion is isothermally stored at a temperature representing the temperature at which a phase-change material transitions between phases. The current research provides a review of how phase transition materials are used in melting and solidification. Generally, the range of working temperature extends from -20 °C to 200 °C for solidification and melting applications. The first range (-20 to 5 °C) is employed for commercial and domestic refrigeration. The second range (5 to 40 °C) is utilized to lower the energy requirements for air-conditioning applications. The applications includes in third range (40 to 82 °C) are solar collector and heating of water. Applications of absorption cooling, waste electricity generations, and heat recovery are operated at high temperature range (82 to180 °C). There are various types of PCMs for all the above temperature ranges. The present review paper will discuss the application field, Geometry, PCM type, heat transfer augmentation technique and their effects on the performance. The conclusions are mentioned to give more insight about the PCM behavior in various applications.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42904218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-31DOI: 10.18186/thermal.1245331
P. Ben Ishai
Kaur and Khan have published a simulation study demonstrating that a 5G device should cause only minimal temperature variations in the skin layer. For this they use a 4 - layer skin model and the Pennes’ bioheat equation. The comment points out some differences between the 4 layered model they used and those of the groups of Abdulhalim and Feldman, who also incorporated the presence of the human sweat duct in the model. Furthermore, the comment notes that theoretical work by Neufeld and Kuster that takes into account the disparity between the time constants for electromagnetic absorption and thermal perfusion will lead to significantly higher temperature spikes that those found by the authors. Finally, new research by Gultekin and Siegel is noted that does indeed confirm temperature spikes in biological tissues for 5G frequencies.
{"title":"Comment on “numerical analysis of heat transfer in multilayered skin tissue exposed to 5G mobile communication frequencies” by Jagbir Kaur and S.A. Khan","authors":"P. Ben Ishai","doi":"10.18186/thermal.1245331","DOIUrl":"https://doi.org/10.18186/thermal.1245331","url":null,"abstract":"Kaur and Khan have published a simulation study demonstrating that a 5G device should cause only minimal temperature variations in the skin layer. For this they use a 4 - layer skin model and the Pennes’ bioheat equation. The comment points out some differences between the 4 layered model they used and those of the groups of Abdulhalim and Feldman, who also incorporated the presence of the human sweat duct in the model. Furthermore, the comment notes that theoretical work by Neufeld and Kuster that takes into account the disparity between the time constants for electromagnetic absorption and thermal perfusion will lead to significantly higher temperature spikes that those found by the authors. Finally, new research by Gultekin and Siegel is noted that does indeed confirm temperature spikes in biological tissues for 5G frequencies.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46276134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-31DOI: 10.18186/thermal.1245164
Amri Khaoula, Alkama Djamel
The interest to ensure thermal comfort becomes one of the major challenges in the building sector, not only for the quality of interior ambiences, but also to minimize the energy rate consumed for heating and cooling systems. Th s paper presents the advantage of using the adaptive approach and numerical simulation to assess the level of thermal comfort of dwellings of different architectural typology in hot climate. For this purpose, the method is based on in situ measurements effected on two samples of traditional and contemporary typology; using anemometer instrument, where the climatic parameters measured inside and outside samples are: ambient temperature, relative humidity rate and air velocity. The simulation work is performed by Energy-Plus software; consequently experimental tests are realized on the local material in order to know their physical and thermal characteristics. The results obtained demonstrate the efficiency of the traditional passive devices, which are able to provide a comfortable thermal ambience without referring to the air conditioning system, with an operating temperature of 30.5ºC and a satisfaction rate of 80%.
{"title":"Evaluation of summer thermal comfort using in situ measurement and dynamic simulation, hot and arid climate in Algerian Saharan region as a case study","authors":"Amri Khaoula, Alkama Djamel","doi":"10.18186/thermal.1245164","DOIUrl":"https://doi.org/10.18186/thermal.1245164","url":null,"abstract":"The interest to ensure thermal comfort becomes one of the major challenges in the building sector, not only for the quality of interior ambiences, but also to minimize the energy rate consumed for heating and cooling systems. Th s paper presents the advantage of using the adaptive approach and numerical simulation to assess the level of thermal comfort of dwellings of different architectural typology in hot climate. For this purpose, the method is based on in situ measurements effected on two samples of traditional and contemporary typology; using anemometer instrument, where the climatic parameters measured inside and outside samples are: ambient temperature, relative humidity rate and air velocity. The simulation work is performed by Energy-Plus software; consequently experimental tests are realized on the local material in order to know their physical and thermal characteristics. The results obtained demonstrate the efficiency of the traditional passive devices, which are able to provide a comfortable thermal ambience without referring to the air conditioning system, with an operating temperature of 30.5ºC and a satisfaction rate of 80%.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49031336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-31DOI: 10.18186/thermal.1245279
Surender Antil, G. Sachdeva, Avdhesh Sharma
A gasifier employs partial ignition of biomass and conversion to gaseous fuels of high calorific value. Bubbling fluidized bed gasifier is a promising one amongst other gasification technologies like fixed bed, entrained flow etc. It has several noteworthy advantages like large- and small-scale applications, efficient heat and mass transfer rates due its fuel flexibility, low capital and operating costs, etc. However, low mixing rate of biomass feedstock and gasifying agent, high tar content in the product gas and low calorific value of producer gas are some of its limitations which need sincere attention to enhance its performance. The present study analyzes the effect of design variables of the proposed gasifier reactor for different feedstock along with the operating variables on the quality of producer gas. This review paper examines the present global status of biofuels, different types of gasification technologies, approaches adopted for the gasification, different parameters affecting gasification performance, enhancement of product gas conditioning, technical and cost-effective viability and the future prospects of gasification.
{"title":"Advancements and challenges in the fluidized bed gasification system: A comprehensive review","authors":"Surender Antil, G. Sachdeva, Avdhesh Sharma","doi":"10.18186/thermal.1245279","DOIUrl":"https://doi.org/10.18186/thermal.1245279","url":null,"abstract":"A gasifier employs partial ignition of biomass and conversion to gaseous fuels of high calorific value. Bubbling fluidized bed gasifier is a promising one amongst other gasification technologies like fixed bed, entrained flow etc. It has several noteworthy advantages like large- and small-scale applications, efficient heat and mass transfer rates due its fuel flexibility, low capital and operating costs, etc. However, low mixing rate of biomass feedstock and gasifying agent, high tar content in the product gas and low calorific value of producer gas are some of its limitations which need sincere attention to enhance its performance. The present study analyzes the effect of design variables of the proposed gasifier reactor for different feedstock along with the operating variables on the quality of producer gas. This review paper examines the present global status of biofuels, different types of gasification technologies, approaches adopted for the gasification, different parameters affecting gasification performance, enhancement of product gas conditioning, technical and cost-effective viability and the future prospects of gasification.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42995714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-31DOI: 10.18186/thermal.1245130
T. Choudhary, T. Verma, M. Sahu, U. Rajak, Sanyaj Sanyaj
In the area of clean energy production along with higher efficiency, integrated combine power system, specifically gas turbine (GT) cycle with solid oxide fuel (SOFC) system, is gaining the attention of researchers. Thermodynamic modeling for the SOFC-GT hybrid cycle has been presented in this paper. For the proposed hybrid cycle, a high-temperature SOFC has successfully integrated with the recuperated-blade cooled gas turbine cycle. The gas turbine outlet waste heat has perfectly utilized the recuperator to power the fuel cell system. However, to maintain the temperature of the gas turbine blade within the permissible limit, air–film blade cooling scheme has been used. The SOFC-GT hybrid cycle has been operated under steady-state conditions, and a developed MATLAB program has been used to solve the governing equations for the components of the hybrid cycle. The impact of main operating parameters such as the temperature intake turbine (TIT), compression ratio (rpc), fuel utilization ratio (UF), and recirculation ratio are examined. From the obtained result, it can be revealed that the integration of the SOFC has seen significant improves overall hybrid cycle efficiency. The performance of fuel cell (SOFC) increases notably as the level of recuperation increases. To check the influence of main operating parameters, a sensitivity analysis has been performed for the hybrid cycle, and the maximum efficiency of 73% has been achieved. Moreover, to extend this research, an exclusive performance map has been plotted for power plant designers.
{"title":"Thermodynamic sensitivity analysis of SOFC integrated with blade cooled gas turbine hybrid cycle","authors":"T. Choudhary, T. Verma, M. Sahu, U. Rajak, Sanyaj Sanyaj","doi":"10.18186/thermal.1245130","DOIUrl":"https://doi.org/10.18186/thermal.1245130","url":null,"abstract":"In the area of clean energy production along with higher efficiency, integrated combine power system, specifically gas turbine (GT) cycle with solid oxide fuel (SOFC) system, is gaining the attention of researchers. Thermodynamic modeling for the SOFC-GT hybrid cycle has been presented in this paper. For the proposed hybrid cycle, a high-temperature SOFC has successfully integrated with the recuperated-blade cooled gas turbine cycle. The gas turbine outlet waste heat has perfectly utilized the recuperator to power the fuel cell system. However, to maintain the temperature of the gas turbine blade within the permissible limit, air–film blade cooling scheme has been used. The SOFC-GT hybrid cycle has been operated under steady-state conditions, and a developed MATLAB program has been used to solve the governing equations for the components of the hybrid cycle. The impact of main operating parameters such as the temperature intake turbine (TIT), compression ratio (rpc), fuel utilization ratio (UF), and recirculation ratio are examined. From the obtained result, it can be revealed that the integration of the SOFC has seen significant improves overall hybrid cycle efficiency. The performance of fuel cell (SOFC) increases notably as the level of recuperation increases. To check the influence of main operating parameters, a sensitivity analysis has been performed for the hybrid cycle, and the maximum efficiency of 73% has been achieved. Moreover, to extend this research, an exclusive performance map has been plotted for power plant designers.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46614703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-27DOI: 10.18186/thermal.1243491
Sattar Aljabair, Israa Alesbe, A. Alkhalaf
The virus diffusion in a ventilated room with the droplets produced by coughing and breathing are presented by the Lagrangian model. When the human body is located in the middle of the room with two locations of AC, in front of and behind the human body, three angles of Air Conditioning (AC) gate are applied 0°, 30°, and 60° to show droplet particle diffusion in the room in these cases. Three types of coughing velocity profiles were selected, real human coughing, sinusoidal cough, and cough jet with one velocity profile of breathing as a step function to cover the inhaling and exhaling cycle. The simulation results show that the uncovered standing in the middle of the room, are more susceptible to infection for the bouncy and forced flow around the human body. Droplet particle moves in the room as a random diffusion and it is very sensitive to the thermal load inside the room, generally depends on the bouncy force and pressure force due to convection heat transfer. when the AC location at the opposite direction of coughing flow, the droplet travels a distance of about 3 m, 2.85 m, and 2.75 m for real cough, sinusoidal cough, and cough jet respectively. While the droplet travel distance is about 3.1 m, 3.2 m, and 2.9 m when the AC location is at the same direction of coughing flow. Finally, the adopted CFD modeling was also used to show the effects of different AC locations on coughing, breathing particle droplets distribution in different indoor spaces, such as buildings, hospitals, and public transports, Also, showed good visual demonstration and representation of the real physical processes.
{"title":"CFD modeling of influenza virus diffusion during coughing and breathing in a ventilated room","authors":"Sattar Aljabair, Israa Alesbe, A. Alkhalaf","doi":"10.18186/thermal.1243491","DOIUrl":"https://doi.org/10.18186/thermal.1243491","url":null,"abstract":"The virus diffusion in a ventilated room with the droplets produced by coughing and breathing are presented by the Lagrangian model. When the human body is located in the middle of the room with two locations of AC, in front of and behind the human body, three angles of Air Conditioning (AC) gate are applied 0°, 30°, and 60° to show droplet particle diffusion in the room in these cases. Three types of coughing velocity profiles were selected, real human coughing, sinusoidal cough, and cough jet with one velocity profile of breathing as a step function to cover the inhaling and exhaling cycle. The simulation results show that the uncovered standing in the middle of the room, are more susceptible to infection for the bouncy and forced flow around the human body. Droplet particle moves in the room as a random diffusion and it is very sensitive to the thermal load inside the room, generally depends on the bouncy force and pressure force due to convection heat transfer. when the AC location at the opposite direction of coughing flow, the droplet travels a distance of about 3 m, 2.85 m, and 2.75 m for real cough, sinusoidal cough, and cough jet respectively. While the droplet travel distance is about 3.1 m, 3.2 m, and 2.9 m when the AC location is at the same direction of coughing flow. Finally, the adopted CFD modeling was also used to show the effects of different AC locations on coughing, breathing particle droplets distribution in different indoor spaces, such as buildings, hospitals, and public transports, Also, showed good visual demonstration and representation of the real physical processes.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43230256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-27DOI: 10.18186/thermal.1243481
S. Lahane, P. Deshmukh, Manoj Nargade
In the modern world, with rapid inventions in microscale electronics, devices suffers undesirable internal heat generation and, due to their tiny shapes, undergo large heat flux conditions. This emphasizes the development of effective and efficient heat dissipation methods to boost their performance and keep them in safe working conditions. The jet impingement cooling method is used for cooling purposes in many engineering applications, and is popular for quick removal of heat from the solid surfaces. The present experimental study is an investigation of effect impingement of jet of water and ethylene glycol mixture over a heated surface. The blending of ethylene glycol (C2H6O2) with water (H2O) as a base fluid enhances the average (convective) heat transfer coefficient (HTC). The cooling fluid with different concentrations of C2H6O2 varying from 10%, 25%, 50%, and 100% shows higher values of average convective coefficient at similar flow conditions than pure water. The fluid having mixture proportions 50% C2H6O2 and H2O shows an optimum value for heat transfer enhancement in the range of 30% to 75% than pure water at the same flow rates. It can be noted that based on mechanical stability and the cost associated, the experimental results reveal that the optimum value of the concentration of C2H6O2 in water is 50% for maximum heat transfer and at higher values of C2H6O2 hamper the mechanical stability and causes higher pumping power due to increase in viscosity of the fluid.
{"title":"Experimental investigation for heat transfer augmentation method of jet impingement using a fluid of different concentrations of water and ethylene glycol (EG)","authors":"S. Lahane, P. Deshmukh, Manoj Nargade","doi":"10.18186/thermal.1243481","DOIUrl":"https://doi.org/10.18186/thermal.1243481","url":null,"abstract":"In the modern world, with rapid inventions in microscale electronics, devices suffers undesirable internal heat generation and, due to their tiny shapes, undergo large heat flux conditions. This emphasizes the development of effective and efficient heat dissipation methods to boost their performance and keep them in safe working conditions. The jet impingement cooling method is used for cooling purposes in many engineering applications, and is popular for quick removal of heat from the solid surfaces. The present experimental study is an investigation of effect impingement of jet of water and ethylene glycol mixture over a heated surface. The blending of ethylene glycol (C2H6O2) with water (H2O) as a base fluid enhances the average (convective) heat transfer coefficient (HTC). The cooling fluid with different concentrations of C2H6O2 varying from 10%, 25%, 50%, and 100% shows higher values of average convective coefficient at similar flow conditions than pure water. The fluid having mixture proportions 50% C2H6O2 and H2O shows an optimum value for heat transfer enhancement in the range of 30% to 75% than pure water at the same flow rates. It can be noted that based on mechanical stability and the cost associated, the experimental results reveal that the optimum value of the concentration of C2H6O2 in water is 50% for maximum heat transfer and at higher values of C2H6O2 hamper the mechanical stability and causes higher pumping power due to increase in viscosity of the fluid.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42981069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-27DOI: 10.18186/thermal.1243472
N. Deshmukh, Abhijit Waghmode
Silencer is a device mainly used for attenuation of the engine exhaust noise. Several modifications were attempted to improve the performance of a silencer. In this paper experimental and simulation study was carried out to determine the effect of radial air injection on the temperature and sound pressure level. The radial air injection is introduced in the form of jets inside the silencer. The design of available silencer was studied, and the 3D model was prepared using CATIA software. Simulation study was carried out using ANSYS Fluent, to determine the temperature distribution inside the silencer with and without modification. The radial jets at different pressure were introduced inside the silencer at three different locations. To acquire sound pressure level and temperatures at different locations, Lab View software and FFT analyser were used. The performance of silencer is analysed by comparing temperature of exhaust gases and sound pressure level at constant speed of 3000 rpm. With radial air jets of 2 bar reservoir pressure at three different location Overall Sound Pressure Level reduces by 6 dB and 42 K reduction in temperature of exhaust gases.
{"title":"Control of noise and temperature using radial air injection inside engine silencer","authors":"N. Deshmukh, Abhijit Waghmode","doi":"10.18186/thermal.1243472","DOIUrl":"https://doi.org/10.18186/thermal.1243472","url":null,"abstract":"Silencer is a device mainly used for attenuation of the engine exhaust noise. Several modifications were attempted to improve the performance of a silencer. In this paper experimental and simulation study was carried out to determine the effect of radial air injection on the temperature and sound pressure level. The radial air injection is introduced in the form of jets inside the silencer. The design of available silencer was studied, and the 3D model was prepared using CATIA software. Simulation study was carried out using ANSYS Fluent, to determine the temperature distribution inside the silencer with and without modification. The radial jets at different pressure were introduced inside the silencer at three different locations. To acquire sound pressure level and temperatures at different locations, Lab View software and FFT analyser were used. The performance of silencer is analysed by comparing temperature of exhaust gases and sound pressure level at constant speed of 3000 rpm. With radial air jets of 2 bar reservoir pressure at three different location Overall Sound Pressure Level reduces by 6 dB and 42 K reduction in temperature of exhaust gases.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46826253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-27DOI: 10.18186/thermal.1243502
Meryem Terhan, Sena Saliha Abak
In the study, energy and exergy analysis of the buildings on a campus in Turkey are conducted by using actual operating data and taking measurements in the district heating system as a case study. The energy and exergy demands, losses that stem from all buildings are calculated according to average daily outdoor temperature data. Due to the high heat losses in the buildings, determining the optimal insulation thickness for the exterior wall should be investigated. Therefore, optimal insulation thicknesses, energy savings, fuel consumptions and payback periods of the insulation material on the exterior wall of the building are examined by using Life Cycle Assessment and P1–P2 method for natural gas. Optimal insulation thicknesses are calculated for different insulation materials such as XPS, glass wool, rock wool and EPS for the climatic regions (HDD=800–4250°C days). According to average exergy losses from the building components per unit area, the average total exergy loss is calculated as 2.39×10-2 kW/m2.year and 1.42×10-3 kW/m2 (5.92%) of this loss stems from the exterior walls, 1.93×10-3 kW/m2 (8.07%) from the floors, 7.37×10-4 kW/m2 (3.08%) from the roofs, 1.58×10-2 kW/m2 (65.99%) from the windows and doors, 4.04×10-3 kW/m2 (16.92%) from the ventilation with infiltration. Energy requirement values of the building are found between 2.68–25.70 kWh/m3 towards from the warmest to the coldest climatic region for the uninsulated wall. In the un-insulated state, fuel consumption varies between 1.93-18.48 m3/m2 from the warmest to the coldest region. The optimal insulation thickness values of the building’s exterior wall are calculated as between 2.3–10.0 cm according to different climatic regions. In-state of exterior wall insulation of 3 cm, fuel consumption decreases by 46.63%–53.46% compared to different insulation materials and climatic regions compared to the un-insulated state.
{"title":"Energy, exergy analysis and optimization of insulation thickness on buildings in a low-temperature district heating system","authors":"Meryem Terhan, Sena Saliha Abak","doi":"10.18186/thermal.1243502","DOIUrl":"https://doi.org/10.18186/thermal.1243502","url":null,"abstract":"In the study, energy and exergy analysis of the buildings on a campus in Turkey are conducted by using actual operating data and taking measurements in the district heating system as a case study. The energy and exergy demands, losses that stem from all buildings are calculated according to average daily outdoor temperature data. Due to the high heat losses in the buildings, determining the optimal insulation thickness for the exterior wall should be investigated. Therefore, optimal insulation thicknesses, energy savings, fuel consumptions and payback periods of the insulation material on the exterior wall of the building are examined by using Life Cycle Assessment and P1–P2 method for natural gas. Optimal insulation thicknesses are calculated for different insulation materials such as XPS, glass wool, rock wool and EPS for the climatic regions (HDD=800–4250°C days). According to average exergy losses from the building components per unit area, the average total exergy loss is calculated as 2.39×10-2 kW/m2.year and 1.42×10-3 kW/m2 (5.92%) of this loss stems from the exterior walls, 1.93×10-3 kW/m2 (8.07%) from the floors, 7.37×10-4 kW/m2 (3.08%) from the roofs, 1.58×10-2 kW/m2 (65.99%) from the windows and doors, 4.04×10-3 kW/m2 (16.92%) from the ventilation with infiltration. Energy requirement values of the building are found between 2.68–25.70 kWh/m3 towards from the warmest to the coldest climatic region for the uninsulated wall. In the un-insulated state, fuel consumption varies between 1.93-18.48 m3/m2 from the warmest to the coldest region. The optimal insulation thickness values of the building’s exterior wall are calculated as between 2.3–10.0 cm according to different climatic regions. In-state of exterior wall insulation of 3 cm, fuel consumption decreases by 46.63%–53.46% compared to different insulation materials and climatic regions compared to the un-insulated state.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49346424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-27DOI: 10.18186/thermal.1243519
Ramazan KAYABAŞI1, Metin Kaya
One of the parameters affecting the efficiency of photovoltaic (PV) modules and PV systems is the temperature. The factors that increase the temperature in PV modules cause loss of efficiency. In this study, experiments have been conducted with the aim of re ducing the module temperature. For this purpose, four polycrystalline and four monocrystalline PV modules, all with the same features, were used. A pair of polycrystalline and monocrystalline modules were used as reference modules. The aim of this study is to reduce the operating temperature of the modules, while also decreasing the transient temperature fluctuations in the system, in order to prevent the loss of efficiency. For this reason, current, voltage and power values of PV modules have been examined and the relationship between these values and module temperature has been explained. As a result, temperature values were measured at 30-80°C in reference modules, 30-50°C in heat pipe modules, 30-37°C in modules using heat pipes and phase-changing material, and 30-66°C in modules using phase-changing material with flexible surfaces. If the PV module operating temperature is increased by 35°C, the module efficiency decreases by 10%. Heat pipe and PCM balance the temperature in PV/T/PCM monocrystalline and polycrystalline modules. In PV/T/PCM modules, efficiency loss caused by temperature increase is 1%. In addition, electrical energy is produced from the heat accumulated on the surface of the PV module by means of Thermoelectric Generator (TEG). When the temperature difference between the surfaces is 15°C, the naturally cooled TE provides 0.45V energy output, while the forced-cooled TEG provides 0.97V energy output. As the temperature gap between the surfaces increases, the voltage and current values of the TEG also increase. Briefly, TEG’s power values increase up to 5W depending on the temperature gap between surfaces.
{"title":"Effect of module operating temperature on module efficiency in photovoltaic modules and recovery of photovoltaic module heat by thermoelectric effect","authors":"Ramazan KAYABAŞI1, Metin Kaya","doi":"10.18186/thermal.1243519","DOIUrl":"https://doi.org/10.18186/thermal.1243519","url":null,"abstract":"One of the parameters affecting the efficiency of photovoltaic (PV) modules and PV systems is the temperature. The factors that increase the temperature in PV modules cause loss of efficiency. In this study, experiments have been conducted with the aim of re ducing the module temperature. For this purpose, four polycrystalline and four monocrystalline PV modules, all with the same features, were used. A pair of polycrystalline and monocrystalline modules were used as reference modules. The aim of this study is to reduce the operating temperature of the modules, while also decreasing the transient temperature fluctuations in the system, in order to prevent the loss of efficiency. For this reason, current, voltage and power values of PV modules have been examined and the relationship between these values and module temperature has been explained. As a result, temperature values were measured at 30-80°C in reference modules, 30-50°C in heat pipe modules, 30-37°C in modules using heat pipes and phase-changing material, and 30-66°C in modules using phase-changing material with flexible surfaces. If the PV module operating temperature is increased by 35°C, the module efficiency decreases by 10%. Heat pipe and PCM balance the temperature in PV/T/PCM monocrystalline and polycrystalline modules. In PV/T/PCM modules, efficiency loss caused by temperature increase is 1%. In addition, electrical energy is produced from the heat accumulated on the surface of the PV module by means of Thermoelectric Generator (TEG). When the temperature difference between the surfaces is 15°C, the naturally cooled TE provides 0.45V energy output, while the forced-cooled TEG provides 0.97V energy output. As the temperature gap between the surfaces increases, the voltage and current values of the TEG also increase. Briefly, TEG’s power values increase up to 5W depending on the temperature gap between surfaces.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43350372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：