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Articles 6271 - 6300 of 50088
Full-Text Articles in Entire DC Network
Latent Heat Energy Storage In A Household Refrigerator Powered By Photovoltaic Electricity – Heat Transfer Design And Technical Viability, Carolina Mira-Hernandez, Cesar A. Isaza-Roldan
Latent Heat Energy Storage In A Household Refrigerator Powered By Photovoltaic Electricity – Heat Transfer Design And Technical Viability, Carolina Mira-Hernandez, Cesar A. Isaza-Roldan
International Refrigeration and Air Conditioning Conference
In remote rural areas without access to the electrical grid, the use of a stand-alone photovoltaic (PV) installation to drive a domestic refrigerator can be a viable option for adequate food preservation. In this application, energy storage, probably in electric batteries, is required to guarantee refrigeration conditions during periods without solar energy availability. However, electric batteries are still costly, have limited lifespan and use materials with restricted availability. Latent heat thermal energy storage (LHTES) can be an alternative to electric batteries with reduced cost and lower environmental impact. The current study presents general design guidelines for a system with a …
R1234ze(E) As Drop-In Replacement For R134a In A Micro-Fin Shell-And-Tube Evaporator: Experimental Tests And Calculation Model, Giuseppe Censi, Andrea Padovan
R1234ze(E) As Drop-In Replacement For R134a In A Micro-Fin Shell-And-Tube Evaporator: Experimental Tests And Calculation Model, Giuseppe Censi, Andrea Padovan
International Refrigeration and Air Conditioning Conference
For the planned phase-down of the hydrofluorocarbon (HFC) R134a in vapor compression cycles, a reasonable and accepted long-term substitute is the hydrofluoro-olefin (HFO) R1234ze(E): due to similar operating pressures of the two fluids, an existing plant can be easily adapted to work with R1234ze(E) as a drop-in replacement for R134a. This works presents a direct comparison of the experimental and calculated performances obtained by using R134a and R1234ze(E) in the same water-cooled chiller at the same operating conditions, focusing on the evaporator, a direct expansion shell-and-tube heat exchanger with micro-fin copper tubes. The working conditions are set to typical air …
Experimental Drying Characteristics Of Fabrics Under Vacuum, William E. Asher, Kashif Nawaz, Cheng-Min Yang, Brian Fricke, Olexiy Buyadgie
Experimental Drying Characteristics Of Fabrics Under Vacuum, William E. Asher, Kashif Nawaz, Cheng-Min Yang, Brian Fricke, Olexiy Buyadgie
International Refrigeration and Air Conditioning Conference
A significant amount of the energy consumed in both residential and commercial sectors is used for clothes drying. In conventional convective clothes drying, hot dry air at atmospheric pressure is passed over and through the clothes in order to remove moisture. Both the heat and water carried out are wasted to ambient resulting in an inefficient process. Additionally, the elevated drying temperatures can damage the fibers of the clothes, reducing their useful lifespan. By drying clothes at pressures below atmospheric, the temperature required to drive out moisture can be reduced. The objective of this study is to investigate the drying …
Thermodynamic Analysis Of Thermo-Vacuum Clothes Drying Operation, Cheng-Min Yang, Kashif Nawaz, William Asher, Brian Fricke, Olexiy Buyadgie, Dmytro Buyadgie, Yaroslav Chudnovsky
Thermodynamic Analysis Of Thermo-Vacuum Clothes Drying Operation, Cheng-Min Yang, Kashif Nawaz, William Asher, Brian Fricke, Olexiy Buyadgie, Dmytro Buyadgie, Yaroslav Chudnovsky
International Refrigeration and Air Conditioning Conference
Clothes drying accounts for a significant amount of energy consumed in residential and commercial sectors. Thermal vacuum clothes drying technology (TVCD) is proposed as an advanced clothes dryer that can significantly reduce the energy requirements by expediting the drying process. In the conventional convective clothes dryer, hot dry air is introduced into the drum which gets in direct contact to dry the clothes. This process is energy inefficient since the significant amount of heat and the water carried out with the exhaust stream are wasted. In contrast to the conventional convective drying technique, the drying mechanism of TVCD is through …
Development Of A High Temperature Water Heat Pump In Vent-Less Dishwasher Application, Daqing Li, Suresh Shivashankar
Development Of A High Temperature Water Heat Pump In Vent-Less Dishwasher Application, Daqing Li, Suresh Shivashankar
International Refrigeration and Air Conditioning Conference
In typical commercial dishwasher application, high temperature water (>82.2°C) is needed for rinse process and electrical booster heater is used to provide such hot water. In the same time, exhausted high humidity hot vapor must be vented out with specially installed hood. This paper presents the development of a high temperature water heat pump to reclaim the heat in the exhaust vapor and deliver high temperature hot water to save electrical energy used in booster heater. While in the same time, the dehumidified exhaust air can be vented directly indoor without a specially installed hood. Both R-134a and R-513A …
Experimental Investigation Of The Heat Conductivity Of Natural Refrigerant Oil Mixtures, Katharina Stoeckel, Ramona Nosbers, Thomas Christiane, Ullrich Hesse
Experimental Investigation Of The Heat Conductivity Of Natural Refrigerant Oil Mixtures, Katharina Stoeckel, Ramona Nosbers, Thomas Christiane, Ullrich Hesse
International Refrigeration and Air Conditioning Conference
The Montreal Protocol and especially the European F-Gas-regulation proclaim the reduction of refrigerants with high global warming potential (GWP). Over the next decades, the phase-down of the production and the use of high GWP hydrofluorocarbons (HFCs) is declared. One viable alternative for HFCs are natural refrigerants and their blends. The modification, optimization as well as the simulation of refrigerant cycles for new refrigerants requires knowledge of the thermophysical properties of the alternative refrigerants and their mixtures with the refrigeration oil. While pure refrigerants are well explored, there is a lack of information about the properties of their blends as well …
Performance Optimization Of Variable Speed Room Air-Conditioner Under Intermediate Speed Working Condition, Lei Zhang, Chunhui Liu
Performance Optimization Of Variable Speed Room Air-Conditioner Under Intermediate Speed Working Condition, Lei Zhang, Chunhui Liu
International Refrigeration and Air Conditioning Conference
Through the method of experiment and simulation, some optimized designs have been carried out to improve the performance in intermediate working conditions during the process of performance matching for APF of R32 variable speed room air-conditioner. In this paper the main reason for the poor performance in intermediate conditions of R32 air conditioning system is clarified by the analysis of the heat exchange between the refrigerant side and the air side, and some optimized designs of the indoor unit heat exchanger's pipeline layout and pipe diameter have been carried out. The optimization results show the performance of the intermediate condition …
Comparison Of Transcritical And Subcritical Heat Pump Systems For Domestic Hot Water Production In Energy Recovery Applications, Emilio Navarro-Peris, Ximo Masip, Francisco Barcelo, Jose M Corberan
Comparison Of Transcritical And Subcritical Heat Pump Systems For Domestic Hot Water Production In Energy Recovery Applications, Emilio Navarro-Peris, Ximo Masip, Francisco Barcelo, Jose M Corberan
International Refrigeration and Air Conditioning Conference
Water-to-Water heat pump (WtWHP) is an efficient alternative to the current technologies used in Domestic Hot Water (DHW) production. However, this application is characterized by high secondary temperature lifts and irregular demands that define critically its design. In order to maximize the efficiency, transcritical cycles coupled to stratified storage tank has been the preferred solution. Nevertheless, recently subcritical cycles with a subcooling control system has been also considered also as a promising alternative because of the cost with the right desing the efficiencies could be in the range of transcritical system. The objective of this work is to compare the …
Theoretical Study Of The Heat Pump Performance For Simultaneous Production Of Space Heating And Domestic Hot Water, Fernando Tello-Oquendo, Daniela Vasconez-Nuñez, Jose M Corberan, Emilio Navarro-Peris
Theoretical Study Of The Heat Pump Performance For Simultaneous Production Of Space Heating And Domestic Hot Water, Fernando Tello-Oquendo, Daniela Vasconez-Nuñez, Jose M Corberan, Emilio Navarro-Peris
International Refrigeration and Air Conditioning Conference
Nowadays, one of the most important challenges in the residential sector is the efficiency improvement of the equipment and systems used for space heating (SH) and domestic hot water (DHW) production. The main objective is to reduce the consumption of fossil fuels and CO2 emissions in these applications. In this context, heat pumps are an effective technology as an alternative to boilers for SH and DHW production. However, the SH demand has a different temperature level than the DWH demand. Generally, the SH demand has a variable temperature level that depends on the type of distribution system (type of building) …
Effect Of Surface Wettability On Droplets Growth During Water Condensation And Initial Droplets Icing, Fuqiang Ren, Ellyn Harges, Lorenzo Cremaschi
Effect Of Surface Wettability On Droplets Growth During Water Condensation And Initial Droplets Icing, Fuqiang Ren, Ellyn Harges, Lorenzo Cremaschi
International Refrigeration and Air Conditioning Conference
Air-source heat pump systems extract heat directly from the cold outdoor ambient and reject heat to the warm indoor environments of residential and commercial buildings. During their winter operation, the outdoor coil often accumulates frost on its surface. Frost acts as an insulator and blocks air passages, reducing the heat transfer rate and increasing the pressure drop of air passing through the coil. Defrost cycles are periodically executed between the heating times to melt the ice, drain the water from the outdoor coil, and free accumulated frost before the heating service can start again. Unfortunately, too many defrost cycles penalize …
Techno-Economic Analysis For Two-Stage Vapor Injected System For Heating Applications, Towhid Parikhani, Ammar Bahman, Davide Ziviani
Techno-Economic Analysis For Two-Stage Vapor Injected System For Heating Applications, Towhid Parikhani, Ammar Bahman, Davide Ziviani
International Refrigeration and Air Conditioning Conference
The rise of energy consumption and environmental concerns necessitate research efforts on optimizing HVAC systems. Air source heat pump systems are widely used as space conditioning systems because of their low cost of installation and the possibility of achieving both heating and cooling from the same device. However, under extreme conditions especially in heating mode, conventional heat pumping systems face challenges when operating in cold climate at ambient temperatures that fall below 0°C (32°F). In this paper, a two-stage vapor injection heat pump system with R-32, R-290 and R-410A as the working fluids, was investigated by considering both single objective …
Design Optimization Of A-Type Heat Exchangers Based On High Performance, Non-Round Tubes, James Tancabel, Vikrant Aute, Jiazhen Ling, Reinhard Radermacher
Design Optimization Of A-Type Heat Exchangers Based On High Performance, Non-Round Tubes, James Tancabel, Vikrant Aute, Jiazhen Ling, Reinhard Radermacher
International Refrigeration and Air Conditioning Conference
Air-to-refrigerant heat exchangers (HXs) have been the topic of considerable research as they are the fundamental heat transfer components of HVAC&R systems. For residential and commercial applications, indoor heat exchangers are often in A-type configurations to reduce air-conditioner system footprint while still delivering the required cooling or heating. Classical HX design practices typically assume a uniform frontal air velocity profile to facilitate the use of conventional tube-fin airside heat transfer and pressure drop correlations for performance prediction. However, it is well-reported throughout the literature that A-type HXs experience significant airflow maldistribution which can severely degrade HX performance. Additionally, recent advancements …
Experimental Evaluation Of Local Air-Side Heat Transfer Coefficient On Single Fins, Min Che, Stefan Elbel
Experimental Evaluation Of Local Air-Side Heat Transfer Coefficient On Single Fins, Min Che, Stefan Elbel
International Refrigeration and Air Conditioning Conference
Quantification of local air-side heat transfer coefficient (HTC) on fin-and-tube heat exchanger fins is a challenging task, especially when the fin geometry is complex. A newly developed experimental method can obtain two-dimensional HTC distribution on fin surfaces with a high resolution (8.9 μm). In this research, a thin (20 μm) yellow coating is sprayed on the surface of the fins. The coated fins were exposed in the wind tunnel which has the tracer gas (50 ppmv ammonia) well mixed in the airflow. During the experiment, the color of coated surface changes from yellow to blue. The rate of local mass …
Effect Of Subcooling Control On Residential Heat Pump Systems’ Performance, Bruno Yuji Kimura De Carvalho, Pega Hrnjak
Effect Of Subcooling Control On Residential Heat Pump Systems’ Performance, Bruno Yuji Kimura De Carvalho, Pega Hrnjak
International Refrigeration and Air Conditioning Conference
An electronic expansion valve can be used to improve efficiency and capacity in residential heat pump system by changing the focus of its control method on condenser subcooling and allowing slightly wet compressor suction to reduce discharge temperatures. This paper will present results of an experimental and theoretical analysis of the use of subcooling control. An investigation based on ideal cycle analysis shows potential improvements in HPF can be obtained if the subcooling is controlled by the system’s expansion valve, but higher specific heating capacity and pressure ratios may reduce the overall improvement as outdoor temperatures are further decreased. A …
Experimental And Theoretical Analysis Of Refrigerant Charge Extraction Methods, Luis Sánchez-Moreno Giner, Francisco Barceló Ruescas, Alejandro López Navarro, José Gonzálvez Maciá
Experimental And Theoretical Analysis Of Refrigerant Charge Extraction Methods, Luis Sánchez-Moreno Giner, Francisco Barceló Ruescas, Alejandro López Navarro, José Gonzálvez Maciá
International Refrigeration and Air Conditioning Conference
According to the European Commission, heating, cooling and domestic hot water (DHW) production implies 79% of the total energy consumed in households. Moreover, as 84% of this energy is still generated from fossil fuels, it is required taking measures in order to improve the current situation. One way to increase the decarbonization in households is the use of heat pumps powered by renewable energy sources. Additionally, the energy captured by heat pumps is considered renewable when a certain efficiency value is achieved (2009/28/CE directive). Nowadays, refrigerants used by heat pumps are mainly hydrofluorocarbons (HFCs) which have a high global warming …
An Evaluation Of The Effect Of Corrosion Tests On Thermal Performance Of Aluminum Heat Exchangers, Yupeng Wang, Hui Zhao, Pega Hrnjak
An Evaluation Of The Effect Of Corrosion Tests On Thermal Performance Of Aluminum Heat Exchangers, Yupeng Wang, Hui Zhao, Pega Hrnjak
International Refrigeration and Air Conditioning Conference
This paper shows the impact of the external corrosion generated by SWAAT tests on the thermal performance of the aluminum heat exchangers. The SWAAT tests were designed to evaluate the durability of metallic materials, it could be further utilized to evaluate the effect of corrosion on the thermal and hydraulic performances. The accelerated corrosion test leaves a large amount of salt and corrosion products on the heat exchanger surface. These deposits do not usually occur in operating conditions (some fouling does), they could mislead the understanding of the real effect of corrosion on heat exchanger performance. This paper presents experiments …
Durability And Performance Evaluations Of Superhydrophobic And Icephobic Coatings For Tube-Fin Heat Exchangers, Colin Lee, Evan Hess, Sara Beaini, Song Li, Daniel Bacellar, Dennis Nasuta, Cara Martin
Durability And Performance Evaluations Of Superhydrophobic And Icephobic Coatings For Tube-Fin Heat Exchangers, Colin Lee, Evan Hess, Sara Beaini, Song Li, Daniel Bacellar, Dennis Nasuta, Cara Martin
International Refrigeration and Air Conditioning Conference
Mitigating frost on heat exchanger coils is key for developing high-efficiency heat pumps and enabling the widespread adoption of cold-climate heat pumps. Frost reduces heat exchanger (HX) performance by impeding airflow and adding thermal resistance, therefore taxing the system to consume more energy to satisfy temperature setpoints. Accordingly, heat pump systems have defrost cycles, which typically involve electrical heaters or hot-gas bypass systems, that consume extra energy to melt away the impeding frost/ice layer on coils. As presented in prior literature, enhanced HX surfaces (such as louvered fins or increased fin density) can accelerate frost development and thus have faster …
A Critical Literature Review Of Defrost Technologies For Heat Pumps And Refrigeration Systems, Kashif Nawaz, Brian Fricke
A Critical Literature Review Of Defrost Technologies For Heat Pumps And Refrigeration Systems, Kashif Nawaz, Brian Fricke
International Refrigeration and Air Conditioning Conference
When the operating conditions are extremely cold and humid and the surface temperature of the heat exchanger well below the freezing point (lower than the dew point temperature of the air) moisture from the air stream will freeze on the surface after condensation and the frost will start growing. The frost growth degrades the performance of the system considerably. It hinders the airflow and increases the pressure drop through the coil which means more fan power is requires for to maintain the desired flow rate. With reduced flow rate due to the increase of pressure drop, system’s capacity drops rapidly. …
Upgraded Algebraic Solution For Isobutane Flows In Diabatic Capillary Tubes, Luka Lorbek, Christian Hermes, Joaquim Gonçalves
Upgraded Algebraic Solution For Isobutane Flows In Diabatic Capillary Tubes, Luka Lorbek, Christian Hermes, Joaquim Gonçalves
International Refrigeration and Air Conditioning Conference
The present work advances an algebraic model for predicting the suction line outlet temperature and the mass flow rate in diabatic capillary tube flows. The proposed solution improved the functionality of an existing model, without significantly increasing the complexity of its implementation. The approach introduced in this paper assumes the refrigerant flow in the capillary tube as adiabatic to describe the two-phase temperature profile. By doing so, the ordinary differential equation governing the energy conservation in the suction line can be solved analytically. The model predictions for the refrigerant mass flow rate and the temperature difference through the suction line …
Design Optimization Of 3mm And 5mm Copper Tube And Flat Fin Air-To-Water Heat Exchangers With Experimental Validation, Daniel Bacellar, Dennis Nasuta, Song Li, Cara Martin, Dale Powell
Design Optimization Of 3mm And 5mm Copper Tube And Flat Fin Air-To-Water Heat Exchangers With Experimental Validation, Daniel Bacellar, Dennis Nasuta, Song Li, Cara Martin, Dale Powell
International Refrigeration and Air Conditioning Conference
The literature has extensively demonstrated the benefits of tube diameter reduction for enhancing airside thermal performance, increasing overall compactness and potential refrigerant charge reduction in air-to-refrigerant heat exchangers. The first part of this work consisted of a numerical design optimization of an air-to-water heat exchanger using 3mm and 5mm diameter tubes with same face and surface areas. The purpose is to demonstrate that when all geometric characteristics are kept constant, the smaller tube diameter has always greater thermal-hydraulic performance. The results showed that for the same air pressure drop, the 3mm diameter tube heat exchanger has up to 15% more …
Lubrication Quality Of Compressor Rolling Bearings With Oil-Refrigerant Mixtures, Rudolf Hauleitner, Guillermo E. Morales-Espejel
Lubrication Quality Of Compressor Rolling Bearings With Oil-Refrigerant Mixtures, Rudolf Hauleitner, Guillermo E. Morales-Espejel
International Compressor Engineering Conference
Rolling bearings in refrigerant compressors are lubricated with a mixture of oil and refrigerant. This has always represented a challenge for the bearing lubrication quality estimation (e.g.: kappa or lambda parameters). Even if the mixture rate is known, the exact effect on the lubricant film thickness remains doubtful due to the unknown piezoviscosity and compressibility of the refrigerant and their variation with pressure and temperature. In this work, existing mixing laws for viscosity and piezo-viscosity are examined and adapted to better represent existing measurements. The results are compared with published Daniel plots showing reasonable agreement. Once this is done a …
Integrated Thermal Energy Storage System For Air-Conditioners With Phase-Change Composites, Anurag Goyal, Eric Kozubal, Jason Woods
Integrated Thermal Energy Storage System For Air-Conditioners With Phase-Change Composites, Anurag Goyal, Eric Kozubal, Jason Woods
International Refrigeration and Air Conditioning Conference
Thermal energy storage (TES) is a promising solution to store and dispatch energy and shave peak electric load, reducing the operational cost of HVAC systems. We present results of a TES system using phase-change materials (PCM) integrated with an air conditioner. The proposed system uses an organic PCM (tetradecane) encapsulated within compressed expanded natural graphite foams referred to as phase-change composite. The graphite foam encapsulates the PCM eliminating the need for expensive storage vessels, reduces installation costs, and provides higher thermal conductivity that can lead to faster charge/discharge rates. Two serpentines, multi-pass circuits, operating as a heat source and a …
Research On Waste Heat Recovery Of Low Temperature Flue Gas In Cement Plant And New Type Heat Exchange, Zhongbao Liu, Jundi Han, Xin Qi, Bo Zhu, Qingyin Hu
Research On Waste Heat Recovery Of Low Temperature Flue Gas In Cement Plant And New Type Heat Exchange, Zhongbao Liu, Jundi Han, Xin Qi, Bo Zhu, Qingyin Hu
International Refrigeration and Air Conditioning Conference
Based on the measured data of low-temperature waste gas at the outlet of waste heat boiler of a new dry cement production line in a cement factory in China, this paper investigates the utilization of waste heat, and formulates the technical scheme of waste heat utilization, and focuses on the design of the key waste heat exchanger for waste heat utilization, and carries out technical and economic analysis. According to our calculation results, the low-temperature waste heat recovery of cement plant has great potential. Using this technology can save more energy and obtain good economic benefits.In addition, a new type …
Suitable Low Global Warming Potential (Gwp) Refrigerants For Two-Speed Heat Pumps For Residential Applications Based On Simulated Performance, Shen Bo, Moonis Ally, Sharma Vishaldeep
Suitable Low Global Warming Potential (Gwp) Refrigerants For Two-Speed Heat Pumps For Residential Applications Based On Simulated Performance, Shen Bo, Moonis Ally, Sharma Vishaldeep
International Refrigeration and Air Conditioning Conference
The next generation of heat pumps (HPs), including those intended for cold climates must transition to low-global warming potential (GWP) refrigerants to mitigate climate change. HPs must be designed to alleviate the problems of excessive discharge temperatures, low suction pressure and high-pressure ratio at low ambient conditions and insufficient heating capacity relative to the rated heating capacity. In this paper we recognize those concerns. Low global warming potential (GWP) refrigerants are screened based on the shape of their temperature-entropy (T-S) saturation boundary. Simulations of the two-stage HP with low GWP refrigerants (R32, R454B, R466A, and R452B) to replace R-410A was …
Quasi Steady-State Modeling Approach For Low Computational Cost Design Optimization Of Heat Exchangers For Phase Change Material (Pcm) Thermal Batteries, Adam Rhoads, Daniel Bacellar, Cara Martin, Remo Waser, Maurizio Zaglio, Hal Stillman, Jörg Worlitschek, Simon Maranda
Quasi Steady-State Modeling Approach For Low Computational Cost Design Optimization Of Heat Exchangers For Phase Change Material (Pcm) Thermal Batteries, Adam Rhoads, Daniel Bacellar, Cara Martin, Remo Waser, Maurizio Zaglio, Hal Stillman, Jörg Worlitschek, Simon Maranda
International Refrigeration and Air Conditioning Conference
Energy storage devices are key components to enable stable, more efficient, and controllable energy flow in systems. Furthermore, they are facilitators for maximizing the use of renewable primary energy sources, which often do not meet immediate supply-demand needs. Thermal batteries can be configured as tube and flat fin heat exchangers using water as working fluid inside the tubes and surrounded by a Phase-Change Material (PCM) on the external surface. These components typically require transient high-order modeling physics to simulate their behavior that are generally computationally intensive. This paper presents a low computational cost tool for design optimization of the heat …
Condensate Impact On Air Friction Of Plate Fin-Tube Heat Exchangers, Jian Yu
Condensate Impact On Air Friction Of Plate Fin-Tube Heat Exchangers, Jian Yu
International Refrigeration and Air Conditioning Conference
Experimental tests on the air friction of several plate fin-tube heat exchangers were conducted under dry-surface and wet-surface conditions. The impacts of face velocity and condensate rate on the air friction were investigated through the tests. Under dry-surface conditions, the standard face velocity changed from 100 to 2,000 FPM. Under wet-surface conditions, the standard face velocity changed from 300 to 500 FPM. The inlet relative humidity changed from 30% to 90%. Under dry-surface conditions, air-friction is a function of face velocity. Tube size, tube pattern, fin density, number of rows, fin thickness and surface geometry also have an impact on …
Power Electronics High Performance Air-Cooled Heat Sinks Integratinggraphite Based Materials, Carles Oliet, Pablo Castrillo, Eugenio Schillaci, Daniel Santos, Joaquim Rigola, David Mullen, Nathan Cochrane, Connor Mckay, Elvedin Halimic, Klaus Hoell, Florian Preishuber-Pfuegl, Juergen Freismuth, Mathieu Bouton, Marc Pontrucher
Power Electronics High Performance Air-Cooled Heat Sinks Integratinggraphite Based Materials, Carles Oliet, Pablo Castrillo, Eugenio Schillaci, Daniel Santos, Joaquim Rigola, David Mullen, Nathan Cochrane, Connor Mckay, Elvedin Halimic, Klaus Hoell, Florian Preishuber-Pfuegl, Juergen Freismuth, Mathieu Bouton, Marc Pontrucher
International Refrigeration and Air Conditioning Conference
The thermal management of the power electronics cooling in the aircraft is getting more attention in the recent years due to the progressive implementation of electrical systems, especially in the framework of the more electrical aircraft, one of Clean Sky framework research activities to allow Europe to lead the transition to more environmental friendly aircraft in the future. The reference innovative trend in the cooling of power electronics and other semiconductor devices has been to migrate from air cooled solutions to liquid cooled or two-phase flow solutions, as these being able to reach higher levels of heat transfer density and …
Frost Formation In Evaporator Fins With Embedded Negative Stiffness Structures, Aman Thakkar, Jiacheng Ma, Jim Braun, Travis Horton, Andres F. Arrieta
Frost Formation In Evaporator Fins With Embedded Negative Stiffness Structures, Aman Thakkar, Jiacheng Ma, Jim Braun, Travis Horton, Andres F. Arrieta
International Refrigeration and Air Conditioning Conference
Frosting in the evaporator leads to an increase in thermal resistance and reduced airflow, resulting in decreased performance. Traditional thermal defrosting strategies lead to significant energy penalties. Novel shape morphing evaporator fins embedded with multistable structures offer the opportunity for faster defrosting and large energy savings while keeping the capital cost low. This type of morphing fins enables a mechanical defrosting approach that is more effective for higher densities and thicknesses of frost. However, there is a need to better understand frost formation in these structures. In this study, we use a modeling and experimental approach to understand frosting on …
A Hybrid Simulation Model To Predict The Steady-State Thermal Profile Of Hermetic Reciprocating Compressors, Fernando A. Aardoom, Victor H. P. Rosa, Cesar J. Deschamps
A Hybrid Simulation Model To Predict The Steady-State Thermal Profile Of Hermetic Reciprocating Compressors, Fernando A. Aardoom, Victor H. P. Rosa, Cesar J. Deschamps
International Compressor Engineering Conference
Numerical simulation models are paramount to design compressors that follow reliability and efficiency requirements. This paper presents a simulation model to predict the steady-state thermal profile of hermetic reciprocating compressors. A finite element method is used to compute the temperature distribution of the solid components and the fluid in the suction and discharge lines, whereas a lumped-parameter formulation is used to evaluate the internal environment temperature and the gas temperature at the end of the compression cycle. The heat transfer between the gas and the solid components is predicted using imposed convective heat transfer coefficients; some of which are estimated …
Study On Bearing Characteristics Of Reciprocating Compressor For Refrigerator, Masanobu Gondo, Hirotaka Kawabata, Hiroto Hayashi
Study On Bearing Characteristics Of Reciprocating Compressor For Refrigerator, Masanobu Gondo, Hirotaka Kawabata, Hiroto Hayashi
International Compressor Engineering Conference
In recent years, in order to reduce the energy consumption of refrigerators through reduction of input power and improved refrigeration capacity, reciprocating compressors are gradually converted to inverter type. Correspondingly, we have studied the sliding bearing characteristics of the crankshaft journal at variable speed which is the key to improving the efficiency of reciprocating compressor. Generally, the characteristics of a sliding bearing are explained with a Stribeck curve. In the fluid lubrication regime, there is sufficient lubricant between metal surfaces. As the rotational speed decreases, the viscous resistance is reduced and it will result in the reduction of friction coefficient. …