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Full-Text Articles in Entire DC Network
Development Of A Refrigerant Distribution Header Applied To Microchannel Heat Exchangers, Tomoki Hirokawa, Kouju Yamada, Yoshio Oritani, Hirokazu Fujino
Development Of A Refrigerant Distribution Header Applied To Microchannel Heat Exchangers, Tomoki Hirokawa, Kouju Yamada, Yoshio Oritani, Hirokazu Fujino
International Refrigeration and Air Conditioning Conference
A microchannel heat exchanger applied to air conditioners has advantages because of its high heat transfer performance. However, there are some challenges to utilize its maximum performance. One of the most important challenges is refrigerant maldistribution resulting in heat transfer deterioration when it is used as an evaporator. The authors proposed a refrigerant distribution header that can be applied to variable capacity air conditioners, named “Refrigerant loop header.” In this paper, the “Refrigerant loop header”, which enables to equally distribute in a wide range of capacity, is introduced. In addition, high distribution performance is experimentally confirmed at different refrigerant mass …
Enhanced Integer Permutation Based Genetic Algorithm For Optimization Of Tube-Fin Heat Exchanger Circuitry With Splits And Merges, Zhenning Li, Vikrant Aute
Enhanced Integer Permutation Based Genetic Algorithm For Optimization Of Tube-Fin Heat Exchanger Circuitry With Splits And Merges, Zhenning Li, Vikrant Aute
International Refrigeration and Air Conditioning Conference
Tube-fin heat exchangers (HXs) are widely used in air-conditioning and heat pump applications. The performance of these heat exchangers is strongly influenced by the refrigerant circuitry. Studies have proved that by optimizing the refrigerant circuitry, the performance of HXs can be significantly improved. In our previous research, an Integer Permutation based Genetic Algorithm (IPGA) was developed to obtain the optimal circuitry designs. Our previous research showed that IPGA demonstrates superior capability to obtain better refrigerant circuitries with lower computational cost than the other methods in literature. And the optimal circuitry designs obtained from IPGA are manufacturable with the available tooling. …
Prediction Of Fin Efficiency, Air Side Heat Transfer Coefficient, And Air Side Pressure Drop Of Flat Tube Heat Exchanger, Akira Yatsuyanagi, Akira Ishibashi, Shin Nakamura
Prediction Of Fin Efficiency, Air Side Heat Transfer Coefficient, And Air Side Pressure Drop Of Flat Tube Heat Exchanger, Akira Yatsuyanagi, Akira Ishibashi, Shin Nakamura
International Refrigeration and Air Conditioning Conference
Heat exchangers equipped with circular tubes are generally used in air conditioners. Recently, air conditioners using heat exchangers equipped with flat tubes for higher performance have been enlarging. It is also effective for increasing the efficiency of the air conditioner to improve the performance by optimal design of the heat exchanger. Therefore, it is important to improve the accuracy of the air side performance prediction method. In this study, we propose a new method to predict air side heat transfer characteristics and air side pressure drop characteristics of the flat tube heat exchanger using the numerical analysis. The calculation results, …
An Infrared Thermography Based Quantification Method Of Two-Phase Refrigerant Distribution In Brazed Plate Heat Exchangers, Wenzhe Li, Pega Hrnjak
An Infrared Thermography Based Quantification Method Of Two-Phase Refrigerant Distribution In Brazed Plate Heat Exchangers, Wenzhe Li, Pega Hrnjak
International Refrigeration and Air Conditioning Conference
When used as direct expansion (DX) evaporators, brazed plate heat exchangers (BPHEs) suffer from the maldistribution of the two-phase refrigerant among parallel plate channels. It is essential to accurately quantify the two-phase refrigerant distribution in BPHEs to evaluate the effect of the maldistribution on the heat exchangers and system performance. Considering the complex internal geometry of BPHEs and the potential influence of experimental measurements on the original flow field, the non-intrusive quantification of the two-phase flow distribution in BPHEs is preferred. This paper presents a method to quantify the two-phase refrigerant distribution in BPHEs from infrared images. Quantification is achieved …
Promoting Equity By Scaling Up Summer Engineering Experiences: A Retrospective Reflection On Tensions And Tradeoffs, Walter C. Lee, David B. Knight, Monica E. Cardella
Promoting Equity By Scaling Up Summer Engineering Experiences: A Retrospective Reflection On Tensions And Tradeoffs, Walter C. Lee, David B. Knight, Monica E. Cardella
Journal of Pre-College Engineering Education Research (J-PEER)
A central challenge in engineering education is providing experiences that are appropriate for and accessible to underserved communities. However, to provide such experiences, we must better understand the process of offering a geographically distributed asset-based out-of-school program. This paper focuses on a collaborative research project that examined the broad implementation of the Summer Engineering Experiences for Kids (SEEK) program organized by the National Society of Black Engineers (NSBE). SEEK is a three-week summer program that engages participants in hands-on, team-based engineering design projects. NSBE’s goal is to make SEEK culturally sustaining, community-connected, and scalable. The purpose of this paper is …
Transnational Latinx Youths’ Workplace Funds Of Knowledge And Implications For Assets-Based, Equity-Oriented Engineering Education, Amy Wilson-Lopez, Jorge Acosta-Feliz
Transnational Latinx Youths’ Workplace Funds Of Knowledge And Implications For Assets-Based, Equity-Oriented Engineering Education, Amy Wilson-Lopez, Jorge Acosta-Feliz
Journal of Pre-College Engineering Education Research (J-PEER)
Due to economic inequality in society, millions of Latinx high school youth work after-school jobs and summer jobs in order to provide additional income for their families. The purpose of this qualitative study, conducted with transnational Latinx youth, was to identify the engineering-related skills and bodies of knowledge they developed and applied while in different workplaces. This study is framed in complementary theories of funds of knowledge, Vygotskian theories of mediated action, and theories of resistant capital. Specifically, this study is based in the premise that youth can develop engineering-related funds of knowledge through tool-mediated, goal-directed activities jointly conducted with …
The Ingenuity Of Everyday Practice: A Framework For Justice-Centered Identity Work In Engineering In The Middle Grades, Angela M. Calabrese Barton, Kathleen Schenkel, Edna Tan
The Ingenuity Of Everyday Practice: A Framework For Justice-Centered Identity Work In Engineering In The Middle Grades, Angela M. Calabrese Barton, Kathleen Schenkel, Edna Tan
Journal of Pre-College Engineering Education Research (J-PEER)
Inequities in opportunities to learn and become in engineering, especially for minoritized youth, are enduring and systemic. How students experience engineering education, through curriculum, pedagogy, and teacher/student interactions, all shape opportunities for identity development. In this paper we draw upon cultural studies and critical ethnography to explore how and why students engage in engineering for sustainable communities and its relationship to their identity work. We ground our work in a justice-centered asset-based stance that centers how people’s lived lives and community wisdom yield powerful forms of cultural knowledge/practice relevant to learning and engaging in science, technology, engineering, and mathematics. We …
Elementary Teacher Adaptations To Engineering Curricula To Leverage Student And Community Resources, Jennifer L. Chiu, Sarah J. Fick, Kevin W. Mcelhaney, Nonye Alozie, Reina Fujii
Elementary Teacher Adaptations To Engineering Curricula To Leverage Student And Community Resources, Jennifer L. Chiu, Sarah J. Fick, Kevin W. Mcelhaney, Nonye Alozie, Reina Fujii
Journal of Pre-College Engineering Education Research (J-PEER)
This paper addresses an important consideration for promoting equitable engineering instruction: understanding how teachers contextualize curricular materials to draw upon student and community resources. We present a descriptive case study of two 5th grade teachers who co-designed a Next Generation Science Standards (NGSS)-aligned curricular unit that integrated science, engineering, and computational modeling. The five-week project challenged students to redesign their school grounds to reduce water runoff and increase accessibility for students with disabilities. The teachers implemented the project with one Grade 5 class with a large proportion of students having individualized learning plans and cultural backgrounds minoritized in science, technology, …
Experimental Investigation Of A Thermally Integrated Carnot Battery Using A Reversible Heat Pump/Organic Rankine Cycle, Olivier Dumont, Antonios Charalampidis, Vincent Lemort
Experimental Investigation Of A Thermally Integrated Carnot Battery Using A Reversible Heat Pump/Organic Rankine Cycle, Olivier Dumont, Antonios Charalampidis, Vincent Lemort
International Refrigeration and Air Conditioning Conference
The growth of renewable energy requires flexible, low-cost and efficient electrical storage systems to balance the mismatch between energy supply and demand. The Carnot battery (or Pumped Thermal Energy Storage) converts electric energy to thermal energy with a heat pump (HP) when electricity production is greater than demand; when electricity demand outstrips production, the Carnot battery generates power from two thermal storage reservoirs (Rankine mode). Classical Carnot batteries architectures do not achieve more than 60% roundtrip electric efficiency. However, innovative architectures, using waste heat recovery (thermally integrated Carnot batteries) are able to reach electrical power production of the power cycle …
Heating And Air-Conditioning Technology For Radiant Heat Recovery In Kiln Wall Of Cement Plant, Zhongbao Liu, Banghua Zhao, Xin Qi
Heating And Air-Conditioning Technology For Radiant Heat Recovery In Kiln Wall Of Cement Plant, Zhongbao Liu, Banghua Zhao, Xin Qi
International Refrigeration and Air Conditioning Conference
There is a large amount of energy waste in the cement production process, in which the waste of rotary kiln heat and the waste of high temperature exhaust gas at the kiln tail are the most serious. Therefore, the full and reasonable utilization of this waste heat resource is an important measure to improve the utilization degree and energy efficiency of waste heat, effectively reduce the heat pollution caused by waste heat emission to the environment, and protect the ecological environment. It is of great significance to realize energy conservation and emission reduction and regional sustainable development. The strategic goals …
Experimental Comparison Of Cycle Modifications To A Multi-Stage Two-Evaporator Transcritical Co2 Refrigeration Cycle, Riley B. Barta, Paige E. Beck, Davide Ziviani, Eckhard A. Groll
Experimental Comparison Of Cycle Modifications To A Multi-Stage Two-Evaporator Transcritical Co2 Refrigeration Cycle, Riley B. Barta, Paige E. Beck, Davide Ziviani, Eckhard A. Groll
International Refrigeration and Air Conditioning Conference
With increasing awareness of the adverse effects of carbon emissions on the environment, researchers within the heating, ventilation, air conditioning, and refrigeration (HVAC&R) community have been pushing for lower global warming potential (GWP) and natural working fluids as well as systems that are more efficient than the higher-GWP systems they replace. One such working fluid is carbon dioxide (CO2). While CO2 has the advantages of being low-cost, non-flammable, and possessing a high volumetric heat capacity, it has a high critical pressure associated with a low critical temperature, thus often necessitating transcritical operation that requires significant compressor input power. As such, …
Energy Efficient, Cost-Effective Power And Co-Generation Technologies: Techno-Environmental Analysis, Praveen Cheekatamarla, Ahmad Abu-Heiba, Kyle Gluesenkamp, Tim Laclair
Energy Efficient, Cost-Effective Power And Co-Generation Technologies: Techno-Environmental Analysis, Praveen Cheekatamarla, Ahmad Abu-Heiba, Kyle Gluesenkamp, Tim Laclair
International Refrigeration and Air Conditioning Conference
Development of energy solutions for addressing grid resiliency and energy efficiency while lowering greenhouse gas emissions is critical in today’s energy scenario. Chemical energy provides on demand power. Cogeneration technologies offer numerous benefits in meeting the growing energy demand while lowering the impact on environment. Utilization of waste heat from prime movers in conjunction with energy efficient heat pumps and renewable photovoltaics is an attractive approach. Efficient utilization of available resources to support current and future building energy needs targeting grid resiliency, energy and environmental security via co-generation approaches is the focus of this study. A detailed techno-environmental analysis of …
Bubble Dynamics Studies In An Absorber With Swirl Entry Of Absorption Refrigeration System, Narasimha Reddy Sanikommu, Mani Annamalai, Tiwari Shaligram
Bubble Dynamics Studies In An Absorber With Swirl Entry Of Absorption Refrigeration System, Narasimha Reddy Sanikommu, Mani Annamalai, Tiwari Shaligram
International Refrigeration and Air Conditioning Conference
Experimental investigations have been carried out on a glass bubble absorber with swirl entry of air to visualize air bubble characteristics. Experiments are carried out in still, co-current and counter-current flow direction of the water. In bubble visualization studies, it was observed that the bubbles forms at the swirl generator surface, grows and detaches the swirl generator surface and moves upwards in water. Effect of air and water flow rate on the bubble detachment diameter was studied. Bubble detachment diameter always increases with air flow rate irrespective of water flow direction. Bubble diameter increases in counter-current flow of water, whereas …
Experimental Characterization Of A Condensing Units’ Performance Under A Controlled Refrigerant Leakage, Etienne Haddad, Assaad Zoughaib
Experimental Characterization Of A Condensing Units’ Performance Under A Controlled Refrigerant Leakage, Etienne Haddad, Assaad Zoughaib
International Refrigeration and Air Conditioning Conference
The European regulation has set a series of limitation to reach the objective of reducing the high Global Warming Potential (GWP) gases emissions. Among these limits, the ban of Hydrofluorocarbons (HFC) refrigerants having a GWP higher than 2500 starting 2020 and a stringent leakage control on refrigeration equipments. Many continuous leakage detection technologies exist but they are not applicable in many cases such as open space or outside equipments. A software based leak detection technique may be interesting in these cases. This technique is based on machine data monitoring and data derived models. In order to be more precise and …
The Life And Legacy Of William Rankine, Andy Pearson
The Life And Legacy Of William Rankine, Andy Pearson
International Refrigeration and Air Conditioning Conference
Professor William Rankine, who was born on July 5 1820, made a substantial contribution to the science of heat and power and his influence in refrigeration and air-conditioning is still apparent today. This paper gives a short overview of Rankine’s life and work and then considers how his legacy is relevant to the challenges facing refrigeration, air conditioning and heat pump engineers in the 21st century. These include system efficiency, expansion methods, alternative cycles and novel working fluids.
Experimental And Numerical Optimization Of A Variable-Geometry Ejector In A Transcritical Co2 Refrigeration Cycle, Riley B. Barta, Parveen Dhillon, Davide Ziviani, James E. Braun, Eckhard A. Groll
Experimental And Numerical Optimization Of A Variable-Geometry Ejector In A Transcritical Co2 Refrigeration Cycle, Riley B. Barta, Parveen Dhillon, Davide Ziviani, James E. Braun, Eckhard A. Groll
International Refrigeration and Air Conditioning Conference
Implementation of an ejector for expansion work recovery in transcritical carbon dioxide (CO2) cycles provides an opportunity to improve the efficiency of these environmentally-friendly refrigeration systems. However, literature outlining an approach to ejector design for a given application is lacking. This paper presents a tool to design a complete ejector applied in a vapor compression cycle. In this work, the developed design tool was validated using experimentally-derived polynomials for air-conditioning conditions. Then, constant values for nozzle and mixing section efficiencies were used as inputs into design tool to broaden the analysis outside of the application boundaries of the experimentally-derived polynomials …
Interactions Between Refrigerant Charge And Other Installation Faults On The Behavior Of A Residential Heat Pump In Cooling Mode, Yifeng Hu, David P. Yuill, Seyed Ali Rooholghodos
Interactions Between Refrigerant Charge And Other Installation Faults On The Behavior Of A Residential Heat Pump In Cooling Mode, Yifeng Hu, David P. Yuill, Seyed Ali Rooholghodos
International Refrigeration and Air Conditioning Conference
The effects of refrigerant charge (CH) faults have been intensively investigated over the past three decades. However, the effect of CH faults in the presence of other faults, like the presence of non-condensable gas (NC), has been seldom studied. The patterns of the effect of CH faults on a system with other faults could be different from that on a fault-free system, which could degrade the performance of fault diagnostic tools and cause improper charging by technicians during installation or service of systems in the field. To address this problem, four common installation faults -improper evaporator airflow (EA), liquid line …
Numerical Analysis For Performance Comparison Between Hybrid Ejector And Conventional Refrigeration Systems, Tokitaka Yoshida, Stefan Elbel
Numerical Analysis For Performance Comparison Between Hybrid Ejector And Conventional Refrigeration Systems, Tokitaka Yoshida, Stefan Elbel
International Refrigeration and Air Conditioning Conference
Recently, the utilization of low-grade thermal energy has gained increased attention as an attractive opportunity to save energy. Heat driven ejector refrigeration systems are among a number of promising solutions for utilizing thermal energy from waste heat. However, the main drawbacks of this system are low efficiency at off-design conditions and difficult controllability. Hybrid ejector refrigeration system is a promising solution for overcoming these drawbacks. In this system, a booster compressor is installed in order to improve the efficiency for a wide range of conditions and substantially improve controllability. In this study, a numerical efficiency analysis for hybrid refrigeration ejector …
Variable Entrained Flow Ejector, Egoi Ortego
Variable Entrained Flow Ejector, Egoi Ortego
International Refrigeration and Air Conditioning Conference
In refrigeration systems ejectors are used to increase the pressure of an entrained or secondary stream using the energy of a high pressure and high temperature primary stream. The lack of flexibility of ejectors contributes to their modest deployment in the refrigeration market and more widely in industry. In general, for gas-gas ejectors, the highest ejector performance is obtained at the critical pressure ratio. For lower pressure ratios the entrainment ratio remains constant, and for higher pressure ratios it drops rapidly to zero. This behavior makes the load control hard to handle. In order to increase the flexibility of ejectors …
The Efficient Computational Tools For The Design Process Of The Transcritical Two-Phase Ejectors For Natural-Based Working Fluids, Jakub Bodys, Michal Palacz, Michal Haida, Jacek Smolka, Andrzej J. Nowak
The Efficient Computational Tools For The Design Process Of The Transcritical Two-Phase Ejectors For Natural-Based Working Fluids, Jakub Bodys, Michal Palacz, Michal Haida, Jacek Smolka, Andrzej J. Nowak
International Refrigeration and Air Conditioning Conference
Naturalbased working fluids for refrigeration are becoming a standard commercial solution due to the dynamic research and development in this area as well as law regulations. The stateoftheart ejector technology for R744 systems reached current status due to a significant interest on modelling approaches and effective regulation concepts. The development path of the fast and efficient design tools based on the numerical simulations could be described as a key feature for the R744 commercial technology. In this study, one of the most effective numerical approaches dedicated for the twophase CO2 ejector design and analysis is discussed. Namely, homogeneous equilibrium and …
Empirical Indicated Loss Analysis Of A Semi-Hermetic Light-Commercial Spool Compressor, Seth Yarborough, Craig R. Bradshaw, Joe Orosz, Greg Kemp
Empirical Indicated Loss Analysis Of A Semi-Hermetic Light-Commercial Spool Compressor, Seth Yarborough, Craig R. Bradshaw, Joe Orosz, Greg Kemp
International Compressor Engineering Conference
An analysis of the indicated losses is presented for a semi-hermetic, light-commercial, prototype, spool compressor. The spool compressor prototype was instrumented with five high-speed pressure sensors, three in the process chamber, one in the discharge valve plenum, and one in the motor cavity. These sensors were triggered with a proximity sensor actuated by means of a custom rotary fixture attached to the compressor motor shaft. This coupling of rotational position and pressure measurements allowed for the development of an indicator (pressure v. volume) diagram for the compression process. Additionally, the added sensor in the discharge valve plenum allowed for a …
Experimental Investigation, In-Situ Monitoring And Modeling Of A Condensing Gas Absorption Heat Pump For Residential Buildings, Camila Dávila Valdebenito, Nicolas Paulus, Vincent Lemort, Cristian Cuevas Barraza
Experimental Investigation, In-Situ Monitoring And Modeling Of A Condensing Gas Absorption Heat Pump For Residential Buildings, Camila Dávila Valdebenito, Nicolas Paulus, Vincent Lemort, Cristian Cuevas Barraza
International Refrigeration and Air Conditioning Conference
Innovative technologies are always matter of study. In this work, an experimental performance analysis of an ammonia-water condensing gas absorption heat pump was conducted. This heat pump has a nominal heating capacity of 18,9 kW and it is designed for domestic hot water and space heating. The tests were carried out in a climatic chamber in order to emulate different outdoor ambient conditions regarding temperature and humidity. Different tests conditions were imposed based on a combination of the EN 12309 requirements and typical weather data for Belgium. Measures of gas consumption, electrical consumption, mass flow rates and temperatures were collected …
Application Of Machine Learning Classification Methods In Fault Detection And Diagnosis Of Rooftop Units, Amir Ebrahimifakhar, David Yuill, Adel Kabirikopaei
Application Of Machine Learning Classification Methods In Fault Detection And Diagnosis Of Rooftop Units, Amir Ebrahimifakhar, David Yuill, Adel Kabirikopaei
International Refrigeration and Air Conditioning Conference
In this paper, a data-driven strategy for fault detection and diagnosis in rooftop air conditioning units, based on machine learning classification methods, is proposed. The strategy formulates the fault detection and diagnosis task as a multi-class classification problem. The focus of this study is on detecting and diagnosing the following common rooftop unit faults: refrigerant undercharge, refrigerant overcharge, compressor valve leakage, liquid-line restriction, condenser fouling, evaporator fouling, and non-condensable gas in the refrigerant. Three classification methods, K-nearest neighbors, logistic regression, and random forests were applied to our dataset, and their performance was compared. Ten-fold cross-validation was used to select tuning …
Multi-Criteria Evaluation Of River Source Heat Pump Systems In Terms Of Life Cycle Performance, Yujun Jung, Hoseong Lee
Multi-Criteria Evaluation Of River Source Heat Pump Systems In Terms Of Life Cycle Performance, Yujun Jung, Hoseong Lee
International High Performance Buildings Conference
In this study, the feasibility of thermal energy utilization in river source was investigated by evaluating the performance of a river source heat pump (RSHP) system. The performance of the RSHP system is evaluated with the validated WSHP model and the actual demand of an office building. The system performance is comprehensively analyzed in terms of the life cycle performance, considering energetic, environmental, and economic metrics. The energy consumption is converted to the primary energy consumption (PEC). The environmental impact is represented as CO2 emissions based on life cycle climate performance (LCCP). The economic feasibility is derived in terms of …
System Designing Of Transcritical Co2 Air Conditioning Systems Using Ejector Performance Maps, Muhammad Haider, Stefan Elbel
System Designing Of Transcritical Co2 Air Conditioning Systems Using Ejector Performance Maps, Muhammad Haider, Stefan Elbel
International Refrigeration and Air Conditioning Conference
Awareness about the climate impact of air conditioning systems has given impetus in developing environment-friendly solutions. The transcritical CO2 cycle with an ejector as a work recovery device has been reported as one of the green solutions in the literature. However, commercial applicability of these systems is limited so far despite their offered potential. One of the major impediments for limited commercial usage is unavailability of a systematic approach for system design that can help system designers in finding the optimum component combination for their application. For materializing system design approach, it is imperative to develop a system model that …
Study On Optimal Middle Temperature Of Cascade-Condenser In Co2/Nh3 Cascade Refrigeration Systems With Two Temperature Ranges, Xi Pan, Shizhong Sun, Haojie Wang, Huagen Wu, Ziwen Xing
Study On Optimal Middle Temperature Of Cascade-Condenser In Co2/Nh3 Cascade Refrigeration Systems With Two Temperature Ranges, Xi Pan, Shizhong Sun, Haojie Wang, Huagen Wu, Ziwen Xing
International Refrigeration and Air Conditioning Conference
This paper analyzes a CO2/NH3 cascade refrigeration system of two temperature range applied in the cold storage. A mathematical model is presented to determine the optimal middle temperatures of the cascade-condenser for obtaining the maximum coefficient of performance (COP) under different operation conditions. Three main parameters including the evaporation temperature in the cold storage, the evaporation temperature in the refrigerated storage and the condensation temperature in the high temperature stage are used to study the optimal middle temperature of CO2 in the cascade-condenser. The results show that the optimal middle temperature increases with the increment of three main parameters. Moreover, …
External Water Subcooling To Improve The Performance Of A Co2 Heat Pump For Water Heating That Uses Greywater As Heat Source, Ramón A. Otón-Martínez, Fernando Illán-Gómez, José Ramón García-Cascales, F. Javier Sánchez-Velasco, Víctor Sena-Cuevas
External Water Subcooling To Improve The Performance Of A Co2 Heat Pump For Water Heating That Uses Greywater As Heat Source, Ramón A. Otón-Martínez, Fernando Illán-Gómez, José Ramón García-Cascales, F. Javier Sánchez-Velasco, Víctor Sena-Cuevas
International Refrigeration and Air Conditioning Conference
The use of CO2 heat pumps for water heating combined with energy recovery from greywater is a promising technology that can help to improve the efficiency of both domestic hot water (DHW) generation and space heating. A key aspect to keep in mind during the design of any CO2 refrigeration or heat pump system is the fact that the optimal gas cooler pressure in a transcritical CO2 cycle is mainly dependent on the refrigerant temperature at the gas cooler outlet. In space heating applications as well as DHW generation, operating conditions require high temperatures of refrigerant at the gas cooler …
Self-Powered Heating: Efficiency Analysis, Kyle R. Gluesenkamp, Tim J. Laclair, Praveen Cheekatamarla, Ahmad Abu-Heiba
Self-Powered Heating: Efficiency Analysis, Kyle R. Gluesenkamp, Tim J. Laclair, Praveen Cheekatamarla, Ahmad Abu-Heiba
International Refrigeration and Air Conditioning Conference
Conventional fuel-fired heating devices such as furnaces, boilers, and water heaters have fuel efficiency less than 100% on the basis of higher heating value. They also require electricity from the electric grid to power parasitic loads such as blowers, pumps, fans, and ignitors. The primary energy efficiency of the device accounts for both fuel used on-site and primary energy used off-site to produce electric power used by the device. This work compares conventional fuel-fired heating devices to two types of self-powered devices. A self-powered device (SPD) integrates a power cycle onboard to eliminate consumption of grid electricity. We assume that …
Experimental Investigation On Organic Rankine Cycle In Off-Design Conditions, Jinwoo Oh, Hoyoung Jeong, Hoseong Lee
Experimental Investigation On Organic Rankine Cycle In Off-Design Conditions, Jinwoo Oh, Hoyoung Jeong, Hoseong Lee
International Refrigeration and Air Conditioning Conference
An experimental study is conducted to investigate the thermal-hydraulic characteristics of organic Rankine cycle in off-design conditions using R245fa as the working fluid. The effects of off-design conditions are monitored by varying the boundary conditions of the system in a total of 97 data sets. The charge distribution in the system is examined by applying the density-volume-measurement method in each component while the void fraction model is used for the prediction of captivated mass inside the heat exchangers. The simulation results of the heat exchanger models were validated with the experimental results within 5% error range. The working fluid charge …
Development Of A Mechanistic Chamber Model Of A Novel Peristaltic Compressor For Air-Conditioning And Refrigeration Applications, Mazharul Islam, Craig R. Bradshaw
Development Of A Mechanistic Chamber Model Of A Novel Peristaltic Compressor For Air-Conditioning And Refrigeration Applications, Mazharul Islam, Craig R. Bradshaw
International Compressor Engineering Conference
The air-conditioning and refrigeration industry are constantly searching for efficiency improvements to vapor compression refrigeration systems. A valve-less compressor with variable volume ratios can significantly increase efficiency and add flexibility to these systems. The novel peristaltic compressor is introduced, which has the ability to operate at variable volume ratios and without valves. This compressor operates by means of a progressively actuated diaphragm that compresses vapor and stimulates flow through a cylindrical chamber. In this study, we will present a discretized thermodynamic model of a peristaltic compressor by splitting the mechanism into a series of conjoined segments. Mass and energy balance …