Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 21 of 21
Full-Text Articles in Entire DC Network
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) …
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.
High Temperature Heat Pump Using Hfo And Hcfo Refrigerants - System Design, Simulation, And First Experimental Results, Cordin Arpagaus, Frédéric Bless, Michael Uhlmann, Elias Büchel, Stefan Frei, Jürg Schiffmann, Stefan Bertsch
High Temperature Heat Pump Using Hfo And Hcfo Refrigerants - System Design, Simulation, And First Experimental Results, Cordin Arpagaus, Frédéric Bless, Michael Uhlmann, Elias Büchel, Stefan Frei, Jürg Schiffmann, Stefan Bertsch
International Refrigeration and Air Conditioning Conference
High temperature heat pumps (HTHPs) with heat sink temperatures in the range of 100 to 160°C are expected to become increasingly commercialized in the coming years. Major applications have been identified, particularly in the food, paper, metal and chemical industries, especially in drying, sterilization, evaporation, and steam generation processes. With the intensification of the F-gas regulations, only refrigerants with low GWP may be used in the near future. Replacement fluids for the currently applied hydrofluorocarbons (HFCs) R245fa and R365mfc are required. The actual research gap in the field of HTHPs is to extend the limits of efficiency and heat sink …
Investigations Of Heat Transfer And Components Efficiencies In Two-Phase Isobutane Injector, Kamil Smierciew, Dariusz Butrymowicz, Mark Bergander, Tomasz Przybylinski
Investigations Of Heat Transfer And Components Efficiencies In Two-Phase Isobutane Injector, Kamil Smierciew, Dariusz Butrymowicz, Mark Bergander, Tomasz Przybylinski
International Refrigeration and Air Conditioning Conference
Renewable energy sources may be applied to drive refrigeration and air-conditioning systems, e.g. solar radiation, geothermal resources, heat derived from biomass or waste heat rejected form various thermal processes. In this case absorption refrigeration systems and ejection systems may be used for cooling applications. In both these systems the crucial problem is the development of a suitable liquid pump. Energy consumption to drive these systems is not a major problem here as in most cases amount of energy required to drive a mechanical pump is a contribution of at most a few percent of the overall energy balance of the …
New Lubricants To Enable Performance, Efficiency, And Reliability, Julie Ann Majurin, Anthony Barthel
New Lubricants To Enable Performance, Efficiency, And Reliability, Julie Ann Majurin, Anthony Barthel
International Refrigeration and Air Conditioning Conference
This paper will highlight case studies of physical and chemical interactions between refrigerants, lubricants, and components in HVACR systems from recent evaluations of new low GWP refrigerants, and will emphasize the value of including lubricants as an integral component of technology and product development roadmaps. Refrigerant/lubricant mixture properties, such as miscibility, solubility, and viscosity, are critical to understand to meet design, operation, and reliability goals of HVACR equipment. In this paper, we will discuss miscibility and solubility challenges of specific new refrigerants, and review how these challenges have been addressed using advanced capabilities and deep understanding. Working viscosity is one …
Flashing Liquid Expander Energy Reduction In Refrigeration Systems, Lance Hays
Flashing Liquid Expander Energy Reduction In Refrigeration Systems, Lance Hays
International Refrigeration and Air Conditioning Conference
Expansion valves in refrigeration systems can be replaced with a flashing liquid expander (FLE) to reduce the energy consumption in refrigeration systems. The original application, pioneered by J.J. Brasz, was for commercial 500 Ton chillers. A reduction in compressor power of 7-8% was obtained. Some 100 of these chillers have been operating for more than 10 years. Recent emphasis on the use of environmentally benign refrigerants have created a renewed interest in energy savings. Some refrigerents such as ammonia, carbon dioxide and propane have high lifts resulting in increased inefficiency due to the isenthalpic expansion valve. Useful power is disipated …
A Low Emission, Electrified Solution For Refrigerated Trucking, Shawn Wilfred Vehr
A Low Emission, Electrified Solution For Refrigerated Trucking, Shawn Wilfred Vehr
International Refrigeration and Air Conditioning Conference
Multiple Factors Are Driving Commercial Trucking Toward Electrified Solutions Which Will Lower Harmful Greenhouse Gas Emissions, Improve Efficiency And Reduce Fuel Consumption. As Part Of This, The Refrigerated Trucking Industry Is Searching For Methods To Meet These New Requirements. Today Most Refrigerated Truck Solutions Use A Diesel Engine To Provide Power For The Refrigeration System. This Diesel Engine Is A Source Of Pollutants Which Are Beginning To Be Federally Regulated By The EPA And State Regulated By Groups Such As The California Air Resource Board (CARB). In Addition, This Diesel Engine Is A Source Of Noise And Excessive Fuel Consumption. …
Free Subcooling With The Sky: Improving The Efficiency Of Air Conditioning Systems, Eli A. Goldstein, Dennis Nasuta, Song Li, Cara Martin, Aaswath Raman
Free Subcooling With The Sky: Improving The Efficiency Of Air Conditioning Systems, Eli A. Goldstein, Dennis Nasuta, Song Li, Cara Martin, Aaswath Raman
International Refrigeration and Air Conditioning Conference
Radiative sky cooling is a passive process that can be harnessed to subcool refrigerants in air conditioning and refrigeration systems, thereby increasing the cooling capacity of the refrigerant, and improving the underlying efficiency of the base cooling system. Here, we demonstrate for the first time the use of a radiative sky cooling-enabled passive fluid cooling panel to improve the efficiency of an air conditioning system by subcooling. The panel’s passive cooling capability is enabled by a multilayer optical film that enables the sky cooling effect 24-hours a day. The film is simultaneously a good reflector of solar energy and a …
Application Of Optimization Of Compressors Used In Air Conditioning Units, Joel Vinod Aralikatti, David Zietlow
Application Of Optimization Of Compressors Used In Air Conditioning Units, Joel Vinod Aralikatti, David Zietlow
International Refrigeration and Air Conditioning Conference
Total life-cycle cost of a system are the costs incurred by the owner over the entire life of the system. The two main components of this are: 1) initial cost: cost to purchase the system, often defined by the total/maximum capacity and quality of the system, and 2) operating cost: the cost of operation over the entire life of the system, defined by the daily usage and the efficiencies of the system and its components. Most compressors are designed by trying to minimize the initial cost. Minimal data are available on the selection of a compressor based on its design …
Model-Based Performance Comparison Of Ammonia Chemisorption Heat Pumps For Cold Climate With Different Working Pairs And Cycle Configurations, Zhiyao Yang, Ming Qu, Kyle Gluesenkamp
Model-Based Performance Comparison Of Ammonia Chemisorption Heat Pumps For Cold Climate With Different Working Pairs And Cycle Configurations, Zhiyao Yang, Ming Qu, Kyle Gluesenkamp
International Refrigeration and Air Conditioning Conference
Sorption heat pumps utilize the thermal effect of the sorbent bonding with the refrigerant (sorbate) through a variety of physio-chemical processes, and when such bonding is due to chemical reaction between solid sorbent and gas refrigerant, the system is known as chemisorption heat pump. The most commonly used refrigerant in chemisorption systems is ammonia, and it can work with a variety of sorbent materials across a wide temperature range. The abundance in working pair selection and the viability of resorption configuration leads to multiple available cycle configurations and working pairs for heat pump system design. Therefore, preliminary evaluation of these …
Characterization Of Nanofluids Formed By Fumed Al2o3 In Water For Geothermal Applications, Sergio Bobbo, Laura Colla, Antonella Barizza, Stefano Rossi, Laura Fedele
Characterization Of Nanofluids Formed By Fumed Al2o3 In Water For Geothermal Applications, Sergio Bobbo, Laura Colla, Antonella Barizza, Stefano Rossi, Laura Fedele
International Refrigeration and Air Conditioning Conference
The European Project Cheap-GSHPs, recently approved, aims at reducing the total cost of shallow geothermal systems by 20-30%, also improving actual drilling/installation technologies and designs of Ground Source Heat Exchangers (GSHEs), in combination with a holistic engineering approach to optimize the entire systems for building and district heating and cooling applications, across the different underground and climate conditions existing within the EU. In this frame, the efficiency of the system heat pump/GSHE will be an important task and a part of this project will be on the analyses of possible alternative secondary fluids to be used in the geothermal probe. …
A Fair Comparison Of Co2 And Propane Used In Light Commercial Applications Featuring Natural Refrigerants, Stefan Elbel, Matej Visek, Pega Hrnjak
A Fair Comparison Of Co2 And Propane Used In Light Commercial Applications Featuring Natural Refrigerants, Stefan Elbel, Matej Visek, Pega Hrnjak
International Refrigeration and Air Conditioning Conference
Light commercial refrigeration units exist for a large variety of different applications and include beverage coolers, ice machines, chilled drink dispensers, and merchandizers and storage units for food items. Among the natural refrigerants available, only propane (R290) and carbon dioxide (CO2, R744) are realistic candidates to replace currently used HFC refrigerants. While many of the thermodynamic and transport properties of R290 are favorable over R744, propane is listed as an ASHRAE A3 refrigerant and therefore bears an inherent flammability risk even when the refrigerant charge is limited to 150 g or less as required by applicable safety standards. While it …
Use Of Nanoparticles In Refrigeration Systems: A Literature Review Paper, Amey Majgaonkar
Use Of Nanoparticles In Refrigeration Systems: A Literature Review Paper, Amey Majgaonkar
International Refrigeration and Air Conditioning Conference
The monetary savings from energy efficient systems & responsibility felt to contribute to save environment are encouraging researchers to use different technologies & advancements in science to make their equipments & systems more & more energy efficient. Refrigeration systems are no exceptions. The advances in nanotechnology have lead to emerging of new generation heat transfer fluids called nanofluids. Researchers are trying to use these nanofluids to improve energy efficiency of refrigeration systems. This paper presents a literature review of the research in this field. This paper briefs about basics, historical developments, nanoparticle production techniques, nanofluids & its preparation method and …
Experimental Study Of Two-Phase Seperators For Vapor Compression Systems In Household Appliances, Jessica Alvarado, Brent Junge, Andrea Kelecy
Experimental Study Of Two-Phase Seperators For Vapor Compression Systems In Household Appliances, Jessica Alvarado, Brent Junge, Andrea Kelecy
International Refrigeration and Air Conditioning Conference
Two-phase separation offers an increase in refrigeration system efficiency with the added benefit of using a passive component. Although, a large amount research has been established in the refrigeration field for high mass flux systems, there is still ample opportunity to expand this application and knowledge in the refrigeration home appliances sector which require lower mass flux. The objective of this study was to evaluate the design of liquid-vapor gravity separators for low mass flux systems (1.5 – 3.5 lbm/ft^2hr). In the experimental method, the independent parameters varied were: Inlet Quality, Inlet Pressure, Inlet Mass Flow, Top Branch Flow Ratio …
Energy Saving Measures For Automotive Air Conditioning (Ac) System In The Tropics, Alison Subiantoro, Kim Tiow Ooi, Ulrich Stimming
Energy Saving Measures For Automotive Air Conditioning (Ac) System In The Tropics, Alison Subiantoro, Kim Tiow Ooi, Ulrich Stimming
International Refrigeration and Air Conditioning Conference
Air conditioning (AC) is an integral component of modern cars in the tropics. However, AC usage in this region consumes a large amount of energy. In conventional internal combustion engine cars, it consumes up to 30% of the fuel, while in battery electric cars, AC may reduce the battery range by up to 40%. Fortunately, there are various ways to improve the efficiency of automotive ACs in the tropics. In this paper, three energy saving measures are discussed. These include a higher indoor temperature setting, a smaller temperature lift and a separate dehumidification system. The study suggests that increasing the …
Analysis And Comparison Of Two-Phase Ejector Performance Metrics For R134a And Co2 Ejectors, Neal Lawrence, Stefan Elbel
Analysis And Comparison Of Two-Phase Ejector Performance Metrics For R134a And Co2 Ejectors, Neal Lawrence, Stefan Elbel
International Refrigeration and Air Conditioning Conference
Two-phase ejectors have been gaining increased attention in recent years due to their ability to directly improve the COP of the cycle. Of common interest in two-phase ejector studies is how the ejector improves cycle COP. However, less emphasis is often given to the performance of the two-phase ejector itself. The amount of COP improvement offered by an ejector cycle is very strongly influenced by the performance of the two-phase ejector; thus, it is important to understand the operation and performance of the two-phase ejector. Defining the performance of a two-phase ejector is not as straightforward as for an isentropic …
Extremely Low Refrigerant Charge Beverage Display Cooler Technology Using Propane, Yadira Padilla Fuentes, Stefan Elbel, Predrag S. Hrnjak
Extremely Low Refrigerant Charge Beverage Display Cooler Technology Using Propane, Yadira Padilla Fuentes, Stefan Elbel, Predrag S. Hrnjak
International Refrigeration and Air Conditioning Conference
The majority of beverage manufacturers prefer natural refrigerants over synthetic refrigerant options as the working fluid for their beverage display cooling equipment. The two major refrigerants considered for these light commercial applications are CO2 (carbon dioxide) and R290 (propane). CO2, used in a transcritical cycle, offers advantages in terms of flammability, however, reduced performance at high ambient temperatures and safety issues related to the high working pressures need to be addressed in order to design efficient and cost-competitive systems. The challenges encountered with CO2 are typically no concern for R290; however, the major risk associated with propane is the flammability …
Comparing R1233zd And R245fa For Low Temperature Orc Applications, Bala V. Datla, Joost J. Brasz
Comparing R1233zd And R245fa For Low Temperature Orc Applications, Bala V. Datla, Joost J. Brasz
International Refrigeration and Air Conditioning Conference
The majority of recently introduced ORC systems use R245fa as working fluid. The lower saturation pressures of R245fa versus R134a allowed the use of existing HVAC electric motors, compressors, evaporators and condensers after minor modifications as ORC electric generators, turbines/expanders, boilers and condensers. At elevated saturation temperatures R245fa turbine/expander equipment matches the power density of R134a HVAC compressors equipment. Refrigerants with still lower saturation pressures such as R123 and the newly developed low GWP fluid DR2 are excellent ORC working fluids but lack the synergy that exists in terms of power density between existing R134a compressors and their R245fa turbine …
Successful Design, Implementation, And Validation Of Transcritical R744 Technology For Beverage Display Coolers, Stefan Elbel, Yadira Padilla Fuentes, Chad D. Bowers, Predrag S. Hrnjak
Successful Design, Implementation, And Validation Of Transcritical R744 Technology For Beverage Display Coolers, Stefan Elbel, Yadira Padilla Fuentes, Chad D. Bowers, Predrag S. Hrnjak
International Refrigeration and Air Conditioning Conference
Glass door merchandisers are used in grocery and convenience stores to display chilled beverages or refrigerated foods. Among other possible choices for this application, carbon dioxide (R744, CO2) is seen as a promising low-GWP refrigerant alternative that is non-flammable and non-toxic. While R744 itself is less costly than synthetic alternatives, successful implementation of high-performance, low-cost transcritical R744 technology is challenging. This paper summarizes important R744-specific design issues and differences in comparison to conventional R134a bottle coolers. Due to cost reasons, it is highly desired to use relatively conventional components, including round-tube-plate-fin heat exchanger designs, fixed geometry capillary tubes (instead of …
Assessment Of Environmentally Friendly Refrigerants For Window Air Conditioners, Bo Shen, Pradeep Bansal
Assessment Of Environmentally Friendly Refrigerants For Window Air Conditioners, Bo Shen, Pradeep Bansal
International Refrigeration and Air Conditioning Conference
Window air conditioners (WAC) are cheap and sold in large numbers internationally as alternatives to central air-conditioning systems. There are nearly 57 million WACs currently operating within United States alone which account for approximately 1.5% of the total US residential energy use or about 0.21 quads per year. Due to global warming and other environmental concerns, there is a need to find an alternative to the currently used refrigerant R410a in WACs. There are several alternative refrigerant options available, including R32, R600a, R290 and R1234yf, but most of these are slightly flammable. Due to the compact size configuration and small …
Refrigerant Distribution Effects On The Performance Of Microchannel Evaporators, Chad D. Bowers, Helena Mai, Stefan Elbel, Predrag S. Hrnjak
Refrigerant Distribution Effects On The Performance Of Microchannel Evaporators, Chad D. Bowers, Helena Mai, Stefan Elbel, Predrag S. Hrnjak
International Refrigeration and Air Conditioning Conference
The performance of air to refrigerant heat exchangers can be affected greatly by both refrigerant and air flow distribution. Maldistribution of either fluid stream can lead to reduced heat transfer effectiveness of the heat exchanger and thus lower system efficiency and capacity. Microchannel evaporators are especially susceptible to refrigerant maldistribution as they typically have many parallel channels fed by a common header or manifold. This paper outlines general trends in refrigerant flow distribution in such evaporators taking into account various heat exchanger orientations. In addition, links between heat exchanger performance and refrigerant flow distribution characteristics in microchannel evaporators are made …