Pub Date : 2021-05-04DOI: 10.1142/S2010132521500139
K. Al‐Chlaihawi, K. Al‐Farhany
In this paper, the performance characteristics of an ejector-expansion refrigeration cycle (EERC) using R410A are investigated in comparison with that using R22 based on first- and second-law persp...
{"title":"A Comprehensive Energetic and Exergetic Analysis of an Ejector Expansion Refrigeration Cycle Using R22 and R410A","authors":"K. Al‐Chlaihawi, K. Al‐Farhany","doi":"10.1142/S2010132521500139","DOIUrl":"https://doi.org/10.1142/S2010132521500139","url":null,"abstract":"In this paper, the performance characteristics of an ejector-expansion refrigeration cycle (EERC) using R410A are investigated in comparison with that using R22 based on first- and second-law persp...","PeriodicalId":13757,"journal":{"name":"International Journal of Air-conditioning and Refrigeration","volume":"21 1","pages":"2150013"},"PeriodicalIF":1.0,"publicationDate":"2021-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86042869","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 : 2021-04-27DOI: 10.1142/S2010132521500188
Mohamed Y. Hashim, H. Sim, I. Im
This paper presents a computational study on the inter-phase heat transfer inside a conical fluidized bed reactor when hot air is introduced through the bottom inlet. Two different diameters, 2.0[Formula: see text]mm and 4.0[Formula: see text]mm glass particles are used as the first and second solid phase and hot air is used as the third phase. A gas–particle heat transfer and particle–particle heat transfer are investigated by using computational fluid dynamics. Euler–Euler two-fluid model is used to describe dynamics of particles and fluid flow in the reactor. We observe that gas–particle heat transfer coefficient is large when solid particle is small. This is the same tendency as the gas–particle heat transfer coefficient when cold air is introduced among hot particles. Particle-to-particle heat transfer depends much on the superficial velocity at the inlet.
{"title":"A Computational Study on Inter-Phase Heat Transfer in a Conical Fluidized Bed Reactor Using Hot Air","authors":"Mohamed Y. Hashim, H. Sim, I. Im","doi":"10.1142/S2010132521500188","DOIUrl":"https://doi.org/10.1142/S2010132521500188","url":null,"abstract":"This paper presents a computational study on the inter-phase heat transfer inside a conical fluidized bed reactor when hot air is introduced through the bottom inlet. Two different diameters, 2.0[Formula: see text]mm and 4.0[Formula: see text]mm glass particles are used as the first and second solid phase and hot air is used as the third phase. A gas–particle heat transfer and particle–particle heat transfer are investigated by using computational fluid dynamics. Euler–Euler two-fluid model is used to describe dynamics of particles and fluid flow in the reactor. We observe that gas–particle heat transfer coefficient is large when solid particle is small. This is the same tendency as the gas–particle heat transfer coefficient when cold air is introduced among hot particles. Particle-to-particle heat transfer depends much on the superficial velocity at the inlet.","PeriodicalId":13757,"journal":{"name":"International Journal of Air-conditioning and Refrigeration","volume":"21 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79369485","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 : 2021-04-07DOI: 10.1142/S2010132521500140
Min Chai, Yu-Hsuan Chang, Chih-Hung Lin, Jin-Cyuan Tsai, Jhen-You Chin, R. N. Inten
The flow velocity profiles in most of the central air-conditioning pipelines are, in general, not fully developed flow and difficult to obtain the accurate flow rates by flowmeters, which are used for measuring average velocity. Especially for being at the outlet of an elbow, the accuracy of flow rate by measurement is quite low. Therefore, there are some limitations for measurements of flow rate and velocity profile by the present flow measuring technologies. The objective of this study was to establish an approach on accurate predictions of velocity profiles at different measured locations of central air-conditioning pipelines for nonuniform flow measurements by simulations of computational Fluid Dynamics (CFD). All the velocity profiles will integrate as a database for predictions by neural network algorithm for smart measurement further. In the present work initially, international experiments were employed to validate the accuracy of CFD approach. The calculations were carried out by different turbulence models. The results compared with the experimental data by Realizable [Formula: see text]-[Formula: see text] turbulence model with less computing resources have great agreements. Realizable [Formula: see text]-[Formula: see text] turbulence model was, therefore, determined for the predictions of central air-conditioning pipeline. According to various pipings and pipe sizes, the results for three cases show that the velocity profiles in the pipelines would not be symmetrical and has strong secondary flow. Therefore, all of the flow profiles would be integrated and analyzed as a database and assist to get accurately the measured locations of ultrasonic flowmeters. Further, this database will be combined with algorithm of artificial neural network for smart predictions.
{"title":"Investigations on Predictions and Characteristics of Flow Field in the Pipelines of Chillers for Measured Locations of Ultrasonic Flowmeters by CFD Approach","authors":"Min Chai, Yu-Hsuan Chang, Chih-Hung Lin, Jin-Cyuan Tsai, Jhen-You Chin, R. N. Inten","doi":"10.1142/S2010132521500140","DOIUrl":"https://doi.org/10.1142/S2010132521500140","url":null,"abstract":"The flow velocity profiles in most of the central air-conditioning pipelines are, in general, not fully developed flow and difficult to obtain the accurate flow rates by flowmeters, which are used for measuring average velocity. Especially for being at the outlet of an elbow, the accuracy of flow rate by measurement is quite low. Therefore, there are some limitations for measurements of flow rate and velocity profile by the present flow measuring technologies. The objective of this study was to establish an approach on accurate predictions of velocity profiles at different measured locations of central air-conditioning pipelines for nonuniform flow measurements by simulations of computational Fluid Dynamics (CFD). All the velocity profiles will integrate as a database for predictions by neural network algorithm for smart measurement further. In the present work initially, international experiments were employed to validate the accuracy of CFD approach. The calculations were carried out by different turbulence models. The results compared with the experimental data by Realizable [Formula: see text]-[Formula: see text] turbulence model with less computing resources have great agreements. Realizable [Formula: see text]-[Formula: see text] turbulence model was, therefore, determined for the predictions of central air-conditioning pipeline. According to various pipings and pipe sizes, the results for three cases show that the velocity profiles in the pipelines would not be symmetrical and has strong secondary flow. Therefore, all of the flow profiles would be integrated and analyzed as a database and assist to get accurately the measured locations of ultrasonic flowmeters. Further, this database will be combined with algorithm of artificial neural network for smart predictions.","PeriodicalId":13757,"journal":{"name":"International Journal of Air-conditioning and Refrigeration","volume":"14 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82486208","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 : 2021-03-31DOI: 10.1142/S2010132521500164
G. Anand, E. Makar
The Absorption Refrigeration Cycle Turbine Inlet Conditioning (ARCTIC) system can chill the inlet air of the turbine to maintain optimum turbine performance at all ambient temperatures. However, turbine characteristics and bell-mouth icing concerns impose a minimum temperature limitation on the chilled air. Performance guarantees may also require maintaining the inlet air temperature within a narrow range throughout the year. These considerations require accurate prediction of the chilling coil performance over a wide range of operating conditions and the development of a robust controls strategy. A modified wet-surface model is used to model the chilling coil performance. The application of the model to a 2110[Formula: see text]kW (600 RT) ARCTIC providing inlet air chilling for a MARS 100 turbine is considered. A control strategy is developed to maintain the inlet air temperature at the desired set point with varying ambient temperatures and chilling loads. The TIAC controls help maintain the inlet air temperature at 7.22∘C to maximize turbine capacity and efficiency during most of the hot/warm days and accommodates 100% turndown. Additional safety measures are incorporated to prevent bell-mouth icing.
{"title":"Chilled Coil Performance Control and Application to Turbine Inlet Air Cooling","authors":"G. Anand, E. Makar","doi":"10.1142/S2010132521500164","DOIUrl":"https://doi.org/10.1142/S2010132521500164","url":null,"abstract":"The Absorption Refrigeration Cycle Turbine Inlet Conditioning (ARCTIC) system can chill the inlet air of the turbine to maintain optimum turbine performance at all ambient temperatures. However, turbine characteristics and bell-mouth icing concerns impose a minimum temperature limitation on the chilled air. Performance guarantees may also require maintaining the inlet air temperature within a narrow range throughout the year. These considerations require accurate prediction of the chilling coil performance over a wide range of operating conditions and the development of a robust controls strategy. A modified wet-surface model is used to model the chilling coil performance. The application of the model to a 2110[Formula: see text]kW (600 RT) ARCTIC providing inlet air chilling for a MARS 100 turbine is considered. A control strategy is developed to maintain the inlet air temperature at the desired set point with varying ambient temperatures and chilling loads. The TIAC controls help maintain the inlet air temperature at 7.22∘C to maximize turbine capacity and efficiency during most of the hot/warm days and accommodates 100% turndown. Additional safety measures are incorporated to prevent bell-mouth icing.","PeriodicalId":13757,"journal":{"name":"International Journal of Air-conditioning and Refrigeration","volume":"108 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87643235","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 : 2021-03-31DOI: 10.1142/S2010132521500176
M. Hassan, A. N. Khalifa, A. Hamed
Water desalination unit powered by renewable energy sources is sometimes needed at places far from the energy grid lines. Consequently, even countries with rich energy resources, such as the Arabian Gulf countries, have shown strong interest in desalination processes that often use renewable energy sources. This work aims to conduct an exergy analysis of solar-powered humidification–dehumidification (HDH) unit. The exergy analysis input data are extracted from a previous work conducted in August 2020 under Baghdad conditions, 33.3∘N latitude and 44.14∘E longitude. The previous work’s HDH unit consisted of six parabolic trough solar collectors (PTSCs), with a total aperture area of 8.76[Formula: see text]m2. Meteonorm v7.3 software was used to obtain the weather data for Baghdad City, Iraq. The HDH unit results had revealed low exergy efficiency, where the maximum overall exergy efficiency was 0.305% at 12.00[Formula: see text]noon, August 17, 2020, when the salty water flow rate was 1 L/min. The unit’s overall exergy efficiencies were 0.09%, 0.16%, 0.31%, and 0.085% when the salty water flow rates were 0.8, 0.9, 1, and 1.2 L/min, respectively. Maximum exergy destructions for the HDH unit components were 0.513, 0.156, 0.332, and 0.304[Formula: see text]kW for solar radiation, dehumidifier, humidifier, and PTSC, for a salty water flow rate of 1[Formula: see text]L/min. In contrast, the overall exergy destruction of the HDH unit was 1.3[Formula: see text]kW.
{"title":"Exergy Analysis of Humidification–Dehumidification Water Desalination Unit Working under Baghdad Conditions","authors":"M. Hassan, A. N. Khalifa, A. Hamed","doi":"10.1142/S2010132521500176","DOIUrl":"https://doi.org/10.1142/S2010132521500176","url":null,"abstract":"Water desalination unit powered by renewable energy sources is sometimes needed at places far from the energy grid lines. Consequently, even countries with rich energy resources, such as the Arabian Gulf countries, have shown strong interest in desalination processes that often use renewable energy sources. This work aims to conduct an exergy analysis of solar-powered humidification–dehumidification (HDH) unit. The exergy analysis input data are extracted from a previous work conducted in August 2020 under Baghdad conditions, 33.3∘N latitude and 44.14∘E longitude. The previous work’s HDH unit consisted of six parabolic trough solar collectors (PTSCs), with a total aperture area of 8.76[Formula: see text]m2. Meteonorm v7.3 software was used to obtain the weather data for Baghdad City, Iraq. The HDH unit results had revealed low exergy efficiency, where the maximum overall exergy efficiency was 0.305% at 12.00[Formula: see text]noon, August 17, 2020, when the salty water flow rate was 1 L/min. The unit’s overall exergy efficiencies were 0.09%, 0.16%, 0.31%, and 0.085% when the salty water flow rates were 0.8, 0.9, 1, and 1.2 L/min, respectively. Maximum exergy destructions for the HDH unit components were 0.513, 0.156, 0.332, and 0.304[Formula: see text]kW for solar radiation, dehumidifier, humidifier, and PTSC, for a salty water flow rate of 1[Formula: see text]L/min. In contrast, the overall exergy destruction of the HDH unit was 1.3[Formula: see text]kW.","PeriodicalId":13757,"journal":{"name":"International Journal of Air-conditioning and Refrigeration","volume":"71 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85754320","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 : 2021-03-31DOI: 10.1142/S2010132521500127
T. Baki
Ammonia is a natural compound, used more and more in refrigeration installations of absorption and vapor compression, component sizing and more particularly evaporators pass by the mastery and prediction of heat transfer. Our study aims to retrieve experimental data from the literature and verify them with known author correlations, and the differences were observed with margins of error; a new correlation has been developed giving convincing results.
{"title":"Pool Boiling of Ammonia, Assessment of Correlations","authors":"T. Baki","doi":"10.1142/S2010132521500127","DOIUrl":"https://doi.org/10.1142/S2010132521500127","url":null,"abstract":"Ammonia is a natural compound, used more and more in refrigeration installations of absorption and vapor compression, component sizing and more particularly evaporators pass by the mastery and prediction of heat transfer. Our study aims to retrieve experimental data from the literature and verify them with known author correlations, and the differences were observed with margins of error; a new correlation has been developed giving convincing results.","PeriodicalId":13757,"journal":{"name":"International Journal of Air-conditioning and Refrigeration","volume":"130 1","pages":"2150012"},"PeriodicalIF":1.0,"publicationDate":"2021-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81828559","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 : 2021-03-31DOI: 10.1142/S2010132521500152
Kawal Preet Singh Khalsa, S. Sadhu
Evaporation of defrosted water in household refrigerators and condenser waste heat utilization has been reported by many researchers but limited literature is available on the study of evaporative cooling in domestic refrigerators (condenser waste heat utilization for defrost water evaporation) with helical coil heat exchangers. This paper is concerned with evaluating domestic refrigerator performance by employing an evaporative helical coil heat exchanger before hot wall condenser which is utilized for evaporation of defrost water and reducing the superheated refrigerant temperature to condensing temperature to reduce the condenser load and improve the overall performance of a domestic refrigerator. Results show that evaporative cooling increases COP of the system by 25.3%, reduces the energy consumption of the refrigerator by 7.3% and the compressor run time by 10.6%. These experimental results also revealed that using two different thermal conductivity tube materials for evaporative helical coil condenser (Copper tube and Zinc coated steel tube) provided with less wall thickness (0.2[Formula: see text]mm) PVC coating results in good agreement for the same evaporation rate of defrosted water.
{"title":"Experimental Study of Domestic Refrigerator Performance Improvement with Evaporative Condenser","authors":"Kawal Preet Singh Khalsa, S. Sadhu","doi":"10.1142/S2010132521500152","DOIUrl":"https://doi.org/10.1142/S2010132521500152","url":null,"abstract":"Evaporation of defrosted water in household refrigerators and condenser waste heat utilization has been reported by many researchers but limited literature is available on the study of evaporative cooling in domestic refrigerators (condenser waste heat utilization for defrost water evaporation) with helical coil heat exchangers. This paper is concerned with evaluating domestic refrigerator performance by employing an evaporative helical coil heat exchanger before hot wall condenser which is utilized for evaporation of defrost water and reducing the superheated refrigerant temperature to condensing temperature to reduce the condenser load and improve the overall performance of a domestic refrigerator. Results show that evaporative cooling increases COP of the system by 25.3%, reduces the energy consumption of the refrigerator by 7.3% and the compressor run time by 10.6%. These experimental results also revealed that using two different thermal conductivity tube materials for evaporative helical coil condenser (Copper tube and Zinc coated steel tube) provided with less wall thickness (0.2[Formula: see text]mm) PVC coating results in good agreement for the same evaporation rate of defrosted water.","PeriodicalId":13757,"journal":{"name":"International Journal of Air-conditioning and Refrigeration","volume":"8 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85097776","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 : 2021-03-26DOI: 10.1142/S2010132521500115
P. E. Naghani, S. A. Zolfaghari, M. Maerefat, J. Toftum, S. M. Hooshmand
This paper presents an experimental study that evaluated the effects of three different non-uniform types of clothing ensembles (Type A: short-sleeve shirt, T-shirt underwear, men’s briefs, straight trousers, socks, shoes; Type B: long-sleeve shirt, T-shirt underwear, men’s briefs, straight trousers; and Type C: long-sleeve shirt, men’s briefs, straight trousers, thick socks, shoes) with almost the same thermal insulation (about 0.52 clo) on the subjects’ local and overall thermal sensation and air movement preference under a desktop local ventilation system. The experiment was conducted in a test chamber with the mean air temperature of [Formula: see text]C and under three supply air temperatures of [Formula: see text]C, [Formula: see text]C, and [Formula: see text]C from a desktop ventilation system. The results revealed that the body segments with the most critical thermal sensation were (i) forearms, hands and arms for the subjects with “A type” clothing ensemble, (ii) feet, hands and forearms for the subjects with “B type” clothing ensemble, and (iii) hands, arms, forearms and chest for the subjects that wore “C type” clothing ensemble. For the three clothing types of “A”, “B” and “C”, the values of overall thermal sensation changed from [Formula: see text]0.63, [Formula: see text]1.25, and [Formula: see text]1.13 at [Formula: see text]C to [Formula: see text]0.31, [Formula: see text]0.31, and [Formula: see text]0.38 at [Formula: see text]C inlet temperature, respectively. Also, the results indicated that upon elevation of the inlet air temperature from [Formula: see text]C to [Formula: see text]C, the percentages of the subjects who preferred less air movement dropped from 63%, 63%, and 50% to 38%, 25%, and 38%, respectively, for wearing “A”, “B” and “C” clothing ensembles.
{"title":"Experimental Investigation of the Effects of Non-Uniform Clothing Ensembles on the Occupants’ Thermal Perceptions under a Local Ventilation System","authors":"P. E. Naghani, S. A. Zolfaghari, M. Maerefat, J. Toftum, S. M. Hooshmand","doi":"10.1142/S2010132521500115","DOIUrl":"https://doi.org/10.1142/S2010132521500115","url":null,"abstract":"This paper presents an experimental study that evaluated the effects of three different non-uniform types of clothing ensembles (Type A: short-sleeve shirt, T-shirt underwear, men’s briefs, straight trousers, socks, shoes; Type B: long-sleeve shirt, T-shirt underwear, men’s briefs, straight trousers; and Type C: long-sleeve shirt, men’s briefs, straight trousers, thick socks, shoes) with almost the same thermal insulation (about 0.52 clo) on the subjects’ local and overall thermal sensation and air movement preference under a desktop local ventilation system. The experiment was conducted in a test chamber with the mean air temperature of [Formula: see text]C and under three supply air temperatures of [Formula: see text]C, [Formula: see text]C, and [Formula: see text]C from a desktop ventilation system. The results revealed that the body segments with the most critical thermal sensation were (i) forearms, hands and arms for the subjects with “A type” clothing ensemble, (ii) feet, hands and forearms for the subjects with “B type” clothing ensemble, and (iii) hands, arms, forearms and chest for the subjects that wore “C type” clothing ensemble. For the three clothing types of “A”, “B” and “C”, the values of overall thermal sensation changed from [Formula: see text]0.63, [Formula: see text]1.25, and [Formula: see text]1.13 at [Formula: see text]C to [Formula: see text]0.31, [Formula: see text]0.31, and [Formula: see text]0.38 at [Formula: see text]C inlet temperature, respectively. Also, the results indicated that upon elevation of the inlet air temperature from [Formula: see text]C to [Formula: see text]C, the percentages of the subjects who preferred less air movement dropped from 63%, 63%, and 50% to 38%, 25%, and 38%, respectively, for wearing “A”, “B” and “C” clothing ensembles.","PeriodicalId":13757,"journal":{"name":"International Journal of Air-conditioning and Refrigeration","volume":"20 1","pages":"2150011"},"PeriodicalIF":1.0,"publicationDate":"2021-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84887913","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 : 2021-03-10DOI: 10.1142/S2010132521500103
Yong-Il Kwon
Air curtains are installed to reduce heat loss due to drafts intruding into the indoor through the open doorways, and play the role of separating two climatic zones and different environmental zones. It is also used to protect the workplace from impurities or to reduce the spread of cigarette smoke in restaurants. Recently, aircraft to provide the individual air barrier by the vertical blowing air curtains have installed a physical barrier in the breathing zone between adjacent seats to protect passengers from COVID-19. The main factors affecting the sealing performance (SP) of the air curtain are the difference of temperature and pressure between indoor and outdoor, and are used to make the proper jet flow an air barrier with the high airtightness. Until now, various types of air curtains are manufactured and sold. Air curtains with the improved SP do not only have a discharge port but also a suction port. This study was conducted to evaluate the SP of the horizontal blowing air curtain according to the discharge pressure, and to select the minimized volume flow rate required for creating the proper zone separation. The volume flow rate of outdoor air intruding into the indoor through the doorways is used to evaluate the SP of the air curtain, and is calculated using the SVE4 proposed by Murakami in this study.
{"title":"Study on the Evaluation of Sealing Performance of Horizontal Blowing Air Curtain Installed in Doorways","authors":"Yong-Il Kwon","doi":"10.1142/S2010132521500103","DOIUrl":"https://doi.org/10.1142/S2010132521500103","url":null,"abstract":"Air curtains are installed to reduce heat loss due to drafts intruding into the indoor through the open doorways, and play the role of separating two climatic zones and different environmental zones. It is also used to protect the workplace from impurities or to reduce the spread of cigarette smoke in restaurants. Recently, aircraft to provide the individual air barrier by the vertical blowing air curtains have installed a physical barrier in the breathing zone between adjacent seats to protect passengers from COVID-19. The main factors affecting the sealing performance (SP) of the air curtain are the difference of temperature and pressure between indoor and outdoor, and are used to make the proper jet flow an air barrier with the high airtightness. Until now, various types of air curtains are manufactured and sold. Air curtains with the improved SP do not only have a discharge port but also a suction port. This study was conducted to evaluate the SP of the horizontal blowing air curtain according to the discharge pressure, and to select the minimized volume flow rate required for creating the proper zone separation. The volume flow rate of outdoor air intruding into the indoor through the doorways is used to evaluate the SP of the air curtain, and is calculated using the SVE4 proposed by Murakami in this study.","PeriodicalId":13757,"journal":{"name":"International Journal of Air-conditioning and Refrigeration","volume":"345 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73923162","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 : 2021-03-01DOI: 10.1142/S2010132521500097
M. Abd-Elhady, E. Bishara, M. A. Halim
Refrigeration and air conditioning cycles consume a large amount of electrical energy and the shortage in traditional sources of energy is the main reasons for governments to use renewable energy. The most power consuming part in the Vapor Compression Cycle (VCC) is the gas compressor. Therefore, the objective of this research is to increase the cooling rate of the VCC using the same compressor, and that is done by heating the refrigerant coming out from the compressor. The proposed cycle is similar to the VCC except that the compression processes is done in two stages, the first stage via a gas compressor and in the second stage by heating the refrigerant under constant volume. The heating process can be done using solar energy. An experimental setup has been developed to study the influence of heating the refrigerant on the cooling rate of the VCC. The heating process is performed after the compressor, and it is done under constant volume in order to increase the pressure of the refrigerant. Four experiments have been performed; the first experiment is a normal VCC, i.e., without heating, while in the second, third and fourth experiments, the refrigerant has been heated to 50∘C, 100∘C and 150∘C, respectively. It has been found that the cooling power increases with the heating temperature. Heating increases the pressure of the refrigerant in VCC, and consequently increases the mass flow rate of the refrigerant that results in an increase in the refrigeration power for the same compressor power. However, the disadvantage of heating the refrigerant is that it increases the evaporator temperature, which limits the possibility of the VCC to be used in freezing applications.
{"title":"Increasing the Cooling Rate of the Vapor Compression Cycle by Heating","authors":"M. Abd-Elhady, E. Bishara, M. A. Halim","doi":"10.1142/S2010132521500097","DOIUrl":"https://doi.org/10.1142/S2010132521500097","url":null,"abstract":"Refrigeration and air conditioning cycles consume a large amount of electrical energy and the shortage in traditional sources of energy is the main reasons for governments to use renewable energy. The most power consuming part in the Vapor Compression Cycle (VCC) is the gas compressor. Therefore, the objective of this research is to increase the cooling rate of the VCC using the same compressor, and that is done by heating the refrigerant coming out from the compressor. The proposed cycle is similar to the VCC except that the compression processes is done in two stages, the first stage via a gas compressor and in the second stage by heating the refrigerant under constant volume. The heating process can be done using solar energy. An experimental setup has been developed to study the influence of heating the refrigerant on the cooling rate of the VCC. The heating process is performed after the compressor, and it is done under constant volume in order to increase the pressure of the refrigerant. Four experiments have been performed; the first experiment is a normal VCC, i.e., without heating, while in the second, third and fourth experiments, the refrigerant has been heated to 50∘C, 100∘C and 150∘C, respectively. It has been found that the cooling power increases with the heating temperature. Heating increases the pressure of the refrigerant in VCC, and consequently increases the mass flow rate of the refrigerant that results in an increase in the refrigeration power for the same compressor power. However, the disadvantage of heating the refrigerant is that it increases the evaporator temperature, which limits the possibility of the VCC to be used in freezing applications.","PeriodicalId":13757,"journal":{"name":"International Journal of Air-conditioning and Refrigeration","volume":"84 1","pages":"2150009"},"PeriodicalIF":1.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74191628","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}
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