Pub Date : 2014-10-03DOI: 10.1080/10789669.2014.939059
Zhongbin Zhang, Ya-Ping Pan, Hu Huang, Qing Jiang
In this article, an all fresh air-handling unit with high sub-cooling degree is presented. In this unit, refrigerant flows through the high-pressure liquid receiver before it goes through the sub-cooler so as to ensure sufficient sub-cooling degree. Based on the experimental comparison between this unit and conventional unit, coupling relationships between condensing temperatures and sub-cooling degrees of these two units are worked out and analyzed. Experimental results and exergy analysis show that, sub-cooling degree drops with the decrease of condensing temperature, and sub-cooling degree of the designed unit is kept over 7°C when the sub-cooling degree of the conventional unit is only close to 0°C. Furthermore, a method of year-round exergy calculation is presented and applied in calculating and analyzing the year-round exergy of the all fresh air-handling unit. Calculation and analysis show that the all fresh air-handling unit designed and investigated in this article has a year-round exergy efficiency of 28.38%, which is 3.17% higher than that of the conventional unit without high sub-cooling degree.
{"title":"Performance experiment of all fresh air-handling unit with high sub-cooling degree and year-round exergy analysis","authors":"Zhongbin Zhang, Ya-Ping Pan, Hu Huang, Qing Jiang","doi":"10.1080/10789669.2014.939059","DOIUrl":"https://doi.org/10.1080/10789669.2014.939059","url":null,"abstract":"In this article, an all fresh air-handling unit with high sub-cooling degree is presented. In this unit, refrigerant flows through the high-pressure liquid receiver before it goes through the sub-cooler so as to ensure sufficient sub-cooling degree. Based on the experimental comparison between this unit and conventional unit, coupling relationships between condensing temperatures and sub-cooling degrees of these two units are worked out and analyzed. Experimental results and exergy analysis show that, sub-cooling degree drops with the decrease of condensing temperature, and sub-cooling degree of the designed unit is kept over 7°C when the sub-cooling degree of the conventional unit is only close to 0°C. Furthermore, a method of year-round exergy calculation is presented and applied in calculating and analyzing the year-round exergy of the all fresh air-handling unit. Calculation and analysis show that the all fresh air-handling unit designed and investigated in this article has a year-round exergy efficiency of 28.38%, which is 3.17% higher than that of the conventional unit without high sub-cooling degree.","PeriodicalId":13238,"journal":{"name":"HVAC&R Research","volume":"262 1","pages":"810 - 818"},"PeriodicalIF":0.0,"publicationDate":"2014-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76631093","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 : 2014-10-03DOI: 10.1080/10789669.2014.945851
R. Powell, B. Jones, M. Hosni
Thousands of people travel by air every day. In 2011, 730 million people traveled on commercial aircraft domestically (BTS 2012). These passengers are confined to a very high-occupant density space for extended periods of time, sometimes over 15 h or more, for international flights. This large volume of travelers, combined with their time spent in close proximity of each other, during flights increases the potential for transmitting diseases, such as severe acute respiratory syndrome (SARS), tuberculosis, swine influenza (H1N1), and avian influenza (H5N1). Consequently, a common concern during commercial flight is disease transfer among passengers. Airborne pathogens travel throughout aircraft cabins much as airborne particles would. To study how these airborne diseases travel, particles were released into a Boeing 767 aircraft cabin mockup, and the particle deposition rates over a variety of locations were measured. In addition to varying the location of measurements, the surface orientation for measurements was changed between horizontal and vertical configurations. The number of particles that deposited onto a clear tape for each location was optically counted using a photographic type microscope. The microscope limited the particle detection size to particles with diameters greater than 3.0 μm. The particle deposition measurements were then compared to previous air concentration measurements taken in the same mockup aircraft cabin. It was found that the surface orientation played a significant role in particle deposition. Nearly a factor of ten differences in particle counts was observed between the vertical and horizontal surface orientations. In addition, the deposition trend in the mockup cabin, left to right for horizontal orientation, reversed when the surface orientation was changed.
{"title":"Measurement of particle deposition rates in a commercial aircraft cabin","authors":"R. Powell, B. Jones, M. Hosni","doi":"10.1080/10789669.2014.945851","DOIUrl":"https://doi.org/10.1080/10789669.2014.945851","url":null,"abstract":"Thousands of people travel by air every day. In 2011, 730 million people traveled on commercial aircraft domestically (BTS 2012). These passengers are confined to a very high-occupant density space for extended periods of time, sometimes over 15 h or more, for international flights. This large volume of travelers, combined with their time spent in close proximity of each other, during flights increases the potential for transmitting diseases, such as severe acute respiratory syndrome (SARS), tuberculosis, swine influenza (H1N1), and avian influenza (H5N1). Consequently, a common concern during commercial flight is disease transfer among passengers. Airborne pathogens travel throughout aircraft cabins much as airborne particles would. To study how these airborne diseases travel, particles were released into a Boeing 767 aircraft cabin mockup, and the particle deposition rates over a variety of locations were measured. In addition to varying the location of measurements, the surface orientation for measurements was changed between horizontal and vertical configurations. The number of particles that deposited onto a clear tape for each location was optically counted using a photographic type microscope. The microscope limited the particle detection size to particles with diameters greater than 3.0 μm. The particle deposition measurements were then compared to previous air concentration measurements taken in the same mockup aircraft cabin. It was found that the surface orientation played a significant role in particle deposition. Nearly a factor of ten differences in particle counts was observed between the vertical and horizontal surface orientations. In addition, the deposition trend in the mockup cabin, left to right for horizontal orientation, reversed when the surface orientation was changed.","PeriodicalId":13238,"journal":{"name":"HVAC&R Research","volume":"20 1","pages":"770 - 779"},"PeriodicalIF":0.0,"publicationDate":"2014-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79105215","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 : 2014-08-31DOI: 10.1080/10789669.2014.957111
S. Janbakhsh, B. Moshfegh
This study presents numerical investigation of an air supply device based on wall confluent jets in a ventilated room. Confluent jets can be described as multiple round jets issuing from supply device apertures. The jets converge, merge, and combine at a certain distance downstream from the supply device and behave as a united jet, or so-called confluent jet. The numerical predictions of the velocity flow field of isothermal confluent jets with three Reynolds-averaged Navier–Stokes turbulence models (renormalization group k-ϵ, realizable k-ϵ, and shear stress transport k-ω) are reported in the present study. The results of the numerical predictions are verified with detailed experimental measurements by a hot wire anemometer and constant temperature anemometers for two airflow rates. The box method is used to provide the inlet boundary conditions. The study of the airflow distribution shows that a primary wall jet (wall confluent jet) exists close to the supply device along the wetted wall, and a secondary wall jet is created after the stagnation region along the floor. It is presented that the flow field of the primary and secondary wall jet predicted by turbulence models is in good agreement with the experimental data. The current study is also compared with the literature in terms of velocity decay and the spreading rate of the primary and secondary wall jet, the results of which are consistent with each other. Velocity decay and the spreading rate of the secondary wall jet in vertical and lateral directions were studied for different inlet airflow rates and inlet discharge heights. The comparative results demonstrate that the flow behavior is nearly independent of the inlet flow rate. Inlet discharge height is found to have impact close to the inlet, where the velocity decays faster when the jet discharges at higher level. The decay tendency is similar as the jet enters into the room for all discharge heights.
{"title":"Numerical study of a ventilation system based on wall confluent jets","authors":"S. Janbakhsh, B. Moshfegh","doi":"10.1080/10789669.2014.957111","DOIUrl":"https://doi.org/10.1080/10789669.2014.957111","url":null,"abstract":"This study presents numerical investigation of an air supply device based on wall confluent jets in a ventilated room. Confluent jets can be described as multiple round jets issuing from supply device apertures. The jets converge, merge, and combine at a certain distance downstream from the supply device and behave as a united jet, or so-called confluent jet. The numerical predictions of the velocity flow field of isothermal confluent jets with three Reynolds-averaged Navier–Stokes turbulence models (renormalization group k-ϵ, realizable k-ϵ, and shear stress transport k-ω) are reported in the present study. The results of the numerical predictions are verified with detailed experimental measurements by a hot wire anemometer and constant temperature anemometers for two airflow rates. The box method is used to provide the inlet boundary conditions. The study of the airflow distribution shows that a primary wall jet (wall confluent jet) exists close to the supply device along the wetted wall, and a secondary wall jet is created after the stagnation region along the floor. It is presented that the flow field of the primary and secondary wall jet predicted by turbulence models is in good agreement with the experimental data. The current study is also compared with the literature in terms of velocity decay and the spreading rate of the primary and secondary wall jet, the results of which are consistent with each other. Velocity decay and the spreading rate of the secondary wall jet in vertical and lateral directions were studied for different inlet airflow rates and inlet discharge heights. The comparative results demonstrate that the flow behavior is nearly independent of the inlet flow rate. Inlet discharge height is found to have impact close to the inlet, where the velocity decays faster when the jet discharges at higher level. The decay tendency is similar as the jet enters into the room for all discharge heights.","PeriodicalId":13238,"journal":{"name":"HVAC&R Research","volume":"131 1","pages":"846 - 861"},"PeriodicalIF":0.0,"publicationDate":"2014-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85601578","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 : 2014-08-18DOI: 10.1080/10789669.2014.929423
Eduard Cubi Montanya, Jaume Salom Tormo, Núria Garrido Soriano
Surgery rooms are a space type with particularly stringent indoor environmental quality (IEQ) requirements (large airflow rates and narrow comfort windows), which translate into high energy use. Due to the unclear IEQ and infection control requirements for surgery rooms in Spain, these spaces are often designed and operated 24 hours per day and 7 days per week, to meet the most stringent recommendations (not only the requirements) in the available standards and guidelines. This paper critically reviews the Spanish mandatory requirements for surgery rooms by comparing them against their performance motivation and other international standards. Regulatory ambiguities and code-compliant energy efficiency opportunities are identified. The requirements and recommendations in the standards included in this review differ in their magnitude (particularly the airflow requirements), but are similar in their prescriptive nature. This paper identifies the performance goals associated to the prescriptive requirements, and proposes a method to adjust system operation (outdoor airflow rate, total supply air, indoor air temperature, and indoor air relative humidity) to meet IEQ performance goals while reducing energy use. Further work is required to define operation infection control requirements for the different surgery types and enable a performance based control strategy based on real time particle concentration monitoring.
{"title":"Indoor environmental quality and infection control in surgery rooms: Code requirements vs. performance motivation. A critical review","authors":"Eduard Cubi Montanya, Jaume Salom Tormo, Núria Garrido Soriano","doi":"10.1080/10789669.2014.929423","DOIUrl":"https://doi.org/10.1080/10789669.2014.929423","url":null,"abstract":"Surgery rooms are a space type with particularly stringent indoor environmental quality (IEQ) requirements (large airflow rates and narrow comfort windows), which translate into high energy use. Due to the unclear IEQ and infection control requirements for surgery rooms in Spain, these spaces are often designed and operated 24 hours per day and 7 days per week, to meet the most stringent recommendations (not only the requirements) in the available standards and guidelines. This paper critically reviews the Spanish mandatory requirements for surgery rooms by comparing them against their performance motivation and other international standards. Regulatory ambiguities and code-compliant energy efficiency opportunities are identified. The requirements and recommendations in the standards included in this review differ in their magnitude (particularly the airflow requirements), but are similar in their prescriptive nature. This paper identifies the performance goals associated to the prescriptive requirements, and proposes a method to adjust system operation (outdoor airflow rate, total supply air, indoor air temperature, and indoor air relative humidity) to meet IEQ performance goals while reducing energy use. Further work is required to define operation infection control requirements for the different surgery types and enable a performance based control strategy based on real time particle concentration monitoring.","PeriodicalId":13238,"journal":{"name":"HVAC&R Research","volume":"34 1","pages":"643 - 654"},"PeriodicalIF":0.0,"publicationDate":"2014-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73536353","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 : 2014-08-18DOI: 10.1080/10789669.2014.930604
Mary E. Collins Baugher
In an effort to align the breadth of the journal’s topics with ASHRAE’s vision, members of the editorial board of the HVAC&R Research Journal (ASHRAE’s International Journal for Research) have revised the scope of topics that are suitable for publication in the journal. This modification is an adaption to changes in the field and will enable us to more fully meet the information needs of our growing readership. HVAC&R Research offers comprehensive reporting of original research in science and technology related to the stationary and mobile built environment, including:
{"title":"New HVAC&R Research journal publication guidelines clarify expanded range of acceptable topics","authors":"Mary E. Collins Baugher","doi":"10.1080/10789669.2014.930604","DOIUrl":"https://doi.org/10.1080/10789669.2014.930604","url":null,"abstract":"In an effort to align the breadth of the journal’s topics with ASHRAE’s vision, members of the editorial board of the HVAC&R Research Journal (ASHRAE’s International Journal for Research) have revised the scope of topics that are suitable for publication in the journal. This modification is an adaption to changes in the field and will enable us to more fully meet the information needs of our growing readership. HVAC&R Research offers comprehensive reporting of original research in science and technology related to the stationary and mobile built environment, including:","PeriodicalId":13238,"journal":{"name":"HVAC&R Research","volume":"2 1","pages":"593 - 593"},"PeriodicalIF":0.0,"publicationDate":"2014-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86117323","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 : 2014-08-07DOI: 10.1080/10789669.2014.930280
H. Erden, H. Khalifa, R. Schmidt
Transient thermal events in air-cooled data centers may lead to undesirable operating conditions such as the formation of hot spots and associated degradation of equipment reliability. These transients may be caused by cooling equipment failures, server load changes, or other time-dependent scenarios in data center operations. This paper introduces a fast-executing hybrid computational fluid dynamics (CFD)/Lumped-Capacitance model for predicting server inlet temperatures resulting from common transient events such as server shutdown, partial or total chilled water interruption, or partial or total failure of the computer room air handlers (CRAH). The model uses initial steady-state CFD or experimental data in combination with several lumped-capacitance models of the various thermal masses in the data center, including the servers, the room enclosure, the CRAHs and the underfloor plenum. The inclusion of these thermal capacitances and their associated thermal conductance was found to be an important contributor to the overall transient response of the data center air-space. The model predictions have been compared with experimental data obtained in a three-rack data-center test cell and found to agree well with the experimental measurements. Examples of the application of the model to more realistic data center configurations are also given.
{"title":"A hybrid lumped capacitance-CFD model for the simulation of data center transients","authors":"H. Erden, H. Khalifa, R. Schmidt","doi":"10.1080/10789669.2014.930280","DOIUrl":"https://doi.org/10.1080/10789669.2014.930280","url":null,"abstract":"Transient thermal events in air-cooled data centers may lead to undesirable operating conditions such as the formation of hot spots and associated degradation of equipment reliability. These transients may be caused by cooling equipment failures, server load changes, or other time-dependent scenarios in data center operations. This paper introduces a fast-executing hybrid computational fluid dynamics (CFD)/Lumped-Capacitance model for predicting server inlet temperatures resulting from common transient events such as server shutdown, partial or total chilled water interruption, or partial or total failure of the computer room air handlers (CRAH). The model uses initial steady-state CFD or experimental data in combination with several lumped-capacitance models of the various thermal masses in the data center, including the servers, the room enclosure, the CRAHs and the underfloor plenum. The inclusion of these thermal capacitances and their associated thermal conductance was found to be an important contributor to the overall transient response of the data center air-space. The model predictions have been compared with experimental data obtained in a three-rack data-center test cell and found to agree well with the experimental measurements. Examples of the application of the model to more realistic data center configurations are also given.","PeriodicalId":13238,"journal":{"name":"HVAC&R Research","volume":"14 1","pages":"688 - 702"},"PeriodicalIF":0.0,"publicationDate":"2014-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85499976","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 : 2014-08-07DOI: 10.1080/10789669.2014.924354
Liping Wang, P. Haves
Faults in HVAC systems can have a significant negative impact on energy consumption, indoor thermal comfort, and air quality. Automatic fault detection and diagnosis tools can help commissioning providers, operators, and facility managers efficiently detect and diagnose faults. They also can help satisfy the increasing demand for commissioning. A model-based fault detection and diagnosis (FDD) method was developed to detect faults by comparing model prediction and measurement, and to diagnose faults using a rule-based fuzzy inferencing system. The method includes Monte Carlo analysis to improve the robustness of the fault detection and diagnosis and reduce false alarms. The Monte Carlo analysis is employed not only to predict uncertainties in reference model outputs, based on estimates of uncertainty in each of the measured inputs, but also to determine the confidence levels of fault diagnosis by combining the effects of input uncertainties at different operating points. A simulated variable-air-volume (VAV) system, including detailed component models that can simulate different faults as well as correct operation, was used to test the diagnostic rules and the Monte Carlo analysis included in the method. The effect of uncertainties on fault diagnosis is illustrated for various types of faulty operation.
{"title":"Monte Carlo analysis of the effect of uncertainties on model-based HVAC fault detection and diagnostics","authors":"Liping Wang, P. Haves","doi":"10.1080/10789669.2014.924354","DOIUrl":"https://doi.org/10.1080/10789669.2014.924354","url":null,"abstract":"Faults in HVAC systems can have a significant negative impact on energy consumption, indoor thermal comfort, and air quality. Automatic fault detection and diagnosis tools can help commissioning providers, operators, and facility managers efficiently detect and diagnose faults. They also can help satisfy the increasing demand for commissioning. A model-based fault detection and diagnosis (FDD) method was developed to detect faults by comparing model prediction and measurement, and to diagnose faults using a rule-based fuzzy inferencing system. The method includes Monte Carlo analysis to improve the robustness of the fault detection and diagnosis and reduce false alarms. The Monte Carlo analysis is employed not only to predict uncertainties in reference model outputs, based on estimates of uncertainty in each of the measured inputs, but also to determine the confidence levels of fault diagnosis by combining the effects of input uncertainties at different operating points. A simulated variable-air-volume (VAV) system, including detailed component models that can simulate different faults as well as correct operation, was used to test the diagnostic rules and the Monte Carlo analysis included in the method. The effect of uncertainties on fault diagnosis is illustrated for various types of faulty operation.","PeriodicalId":13238,"journal":{"name":"HVAC&R Research","volume":"11 1","pages":"616 - 627"},"PeriodicalIF":0.0,"publicationDate":"2014-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79459595","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 : 2014-08-07DOI: 10.1080/10789669.2014.925347
Junjun Hu, Oluwaseyi T. Ogunsola, Li Song, R. McPherson, Meijun Zhu, Y. Hong, Sheng Chen
Building energy system retrofit and retro-commissioning projects present tremendous opportunities to save energy. Energy consumption in buildings, especially HVAC systems, is significantly impacted by weather conditions. However, short- or long-term climatic data are frequently missing because of data transmission problems, data quality assurance methods, sensor malfunction, or a host of other reasons. These gaps in climatic data continue to provide challenges for HVAC engineers in monitoring and verifying building energy performance. This article examines eight classical approaches that use Linear interpolation, Lagrange interpolation, and Cubic Spline interpolation techniques, and eleven approaches that use two newly developed methods, i.e., Angle-based interpolation and Corr-based interpolation, to restore up to 24 h of missing dry-bulb temperature data in a time series for use in building performance monitoring and analysis. Eleven one-year hourly data sets are used to evaluate the performance of these 19 different methods. Each method is applied to deal with artificial gaps that are generated randomly. In terms of the difference between estimated values and measured values, two types of comparisons are carried out. The first comparison is conducted with three evaluation indices: MAE, RMSE, and STDBIAS. The second comparison is based on the percentage of the total data that can be estimated by an approach within specific error thresholds, including 1°F (0.56°C), 2°F (1.11°C), 3°F (1.67°C), and 5°F (2.78°C), from measured values. The comparison results show that Linear interpolation performs best when filling 1–2 h gaps, Lagrange interpolation (Lag2L2R) outperforms other methods when gaps are 3–8 h long, and the Corr-based interpolation method (Corr1L1R24Avg) is a better technique for filling 9–24 h gaps. This article presents the first part of the research results through the ASHRAE 1413 research project. The second part of the results focuses on methods to filling long-term dry-bulb temperature gaps.
{"title":"Restoration of 1–24 hour dry-bulb temperature gaps for use in building performance monitoring and analysis—Part I","authors":"Junjun Hu, Oluwaseyi T. Ogunsola, Li Song, R. McPherson, Meijun Zhu, Y. Hong, Sheng Chen","doi":"10.1080/10789669.2014.925347","DOIUrl":"https://doi.org/10.1080/10789669.2014.925347","url":null,"abstract":"Building energy system retrofit and retro-commissioning projects present tremendous opportunities to save energy. Energy consumption in buildings, especially HVAC systems, is significantly impacted by weather conditions. However, short- or long-term climatic data are frequently missing because of data transmission problems, data quality assurance methods, sensor malfunction, or a host of other reasons. These gaps in climatic data continue to provide challenges for HVAC engineers in monitoring and verifying building energy performance. This article examines eight classical approaches that use Linear interpolation, Lagrange interpolation, and Cubic Spline interpolation techniques, and eleven approaches that use two newly developed methods, i.e., Angle-based interpolation and Corr-based interpolation, to restore up to 24 h of missing dry-bulb temperature data in a time series for use in building performance monitoring and analysis. Eleven one-year hourly data sets are used to evaluate the performance of these 19 different methods. Each method is applied to deal with artificial gaps that are generated randomly. In terms of the difference between estimated values and measured values, two types of comparisons are carried out. The first comparison is conducted with three evaluation indices: MAE, RMSE, and STDBIAS. The second comparison is based on the percentage of the total data that can be estimated by an approach within specific error thresholds, including 1°F (0.56°C), 2°F (1.11°C), 3°F (1.67°C), and 5°F (2.78°C), from measured values. The comparison results show that Linear interpolation performs best when filling 1–2 h gaps, Lagrange interpolation (Lag2L2R) outperforms other methods when gaps are 3–8 h long, and the Corr-based interpolation method (Corr1L1R24Avg) is a better technique for filling 9–24 h gaps. This article presents the first part of the research results through the ASHRAE 1413 research project. The second part of the results focuses on methods to filling long-term dry-bulb temperature gaps.","PeriodicalId":13238,"journal":{"name":"HVAC&R Research","volume":"5 1","pages":"594 - 605"},"PeriodicalIF":0.0,"publicationDate":"2014-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74245999","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 : 2014-08-07DOI: 10.1080/10789669.2014.930304
A. Sethi, P. Hrnjak
A quantitative comparison of oil retention and pressure drop characteristics of refrigerants, R1234yf and R134a with POE32 oil in 10.2 mm inside diameter horizontal and vertical suction lines at a saturation temperature of 13°C with 15°C of superheat is presented. High speed videos of the flow were taken to identify the flow regimes as the mass flux was varied. Test results show that for the same system cooling capacity R1234yf and R134a have very similar oil retention; however, the use of R1234yf results in 20% to 30% higher pressure drop. It was also found that inclined suction lines retain more oil than vertical suction lines.
{"title":"Oil retention and pressure drop of R1234yf and R134a with POE ISO 32 in suction lines","authors":"A. Sethi, P. Hrnjak","doi":"10.1080/10789669.2014.930304","DOIUrl":"https://doi.org/10.1080/10789669.2014.930304","url":null,"abstract":"A quantitative comparison of oil retention and pressure drop characteristics of refrigerants, R1234yf and R134a with POE32 oil in 10.2 mm inside diameter horizontal and vertical suction lines at a saturation temperature of 13°C with 15°C of superheat is presented. High speed videos of the flow were taken to identify the flow regimes as the mass flux was varied. Test results show that for the same system cooling capacity R1234yf and R134a have very similar oil retention; however, the use of R1234yf results in 20% to 30% higher pressure drop. It was also found that inclined suction lines retain more oil than vertical suction lines.","PeriodicalId":13238,"journal":{"name":"HVAC&R Research","volume":"73 1","pages":"703 - 720"},"PeriodicalIF":0.0,"publicationDate":"2014-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81533540","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 : 2014-08-07DOI: 10.1080/10789669.2014.929887
Shengwei Wang, X. Xue, Chengchu Yan
Smart grid has been drawing attention particularly when renewable generations are integrated. In order to ensure high power reliability and energy efficiency in an electrical grid, research and application has been conducted at power supply side to solve the grid critical issues: peak load and power imbalance. However, as the major end-users at power demand side, buildings can also play a significant and cost-effective role by making use of their power demand responses. Different demand response programs (e.g., time- and incentive-based) have been developed and applied for encouraging the end-users to change their energy usage behaviors expected by the grid. Generally, buildings are able to limit and/or shift the power demands according to their own considerations under the specific incentives. A comprehensive review on the building power demand response methods is still missing, although research and application has been investigated and conducted on power demand aspects concerning the building system configuration and the control strategies of power demand optimization. This article, therefore, presents a comprehensive review on the strategies, impacts, and benefits of building power demand response in a grid to systematically evaluate and make better use of their demand response potentials. The possibility of developing proper building power demand response strategies for offline and online applications of the smart grid is also discussed.
{"title":"Building power demand response methods toward smart grid","authors":"Shengwei Wang, X. Xue, Chengchu Yan","doi":"10.1080/10789669.2014.929887","DOIUrl":"https://doi.org/10.1080/10789669.2014.929887","url":null,"abstract":"Smart grid has been drawing attention particularly when renewable generations are integrated. In order to ensure high power reliability and energy efficiency in an electrical grid, research and application has been conducted at power supply side to solve the grid critical issues: peak load and power imbalance. However, as the major end-users at power demand side, buildings can also play a significant and cost-effective role by making use of their power demand responses. Different demand response programs (e.g., time- and incentive-based) have been developed and applied for encouraging the end-users to change their energy usage behaviors expected by the grid. Generally, buildings are able to limit and/or shift the power demands according to their own considerations under the specific incentives. A comprehensive review on the building power demand response methods is still missing, although research and application has been investigated and conducted on power demand aspects concerning the building system configuration and the control strategies of power demand optimization. This article, therefore, presents a comprehensive review on the strategies, impacts, and benefits of building power demand response in a grid to systematically evaluate and make better use of their demand response potentials. The possibility of developing proper building power demand response strategies for offline and online applications of the smart grid is also discussed.","PeriodicalId":13238,"journal":{"name":"HVAC&R Research","volume":"62 1","pages":"665 - 687"},"PeriodicalIF":0.0,"publicationDate":"2014-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73791862","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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