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Articles 6301 - 6330 of 50088
Full-Text Articles in Entire DC Network
Evaluation Of Compressor Reliability For Hfo Refrigerants, Arisa Kawae, Hideki Matsuura, Masaru Tanaka
Evaluation Of Compressor Reliability For Hfo Refrigerants, Arisa Kawae, Hideki Matsuura, Masaru Tanaka
International Compressor Engineering Conference
Responses to an international flamework on climate change, such as the Kigali Agreement in 2016, have been discussed in an industrial field. The phase down regulation of CFC and HCFC refrigerant has been discussed and performed under the Montreal Protocol for refrigerants from the viewpoint of ozone layer protection. From the viewpoint of preventing global warming, HFC reduction plans are currently being proposed by North America, Europe, India, etc. within the framework of the Protocol. A developing country where the phase-out of CFCs and HCFCs began in 2013, are growing trend to switch to HFC or HFO mixed refrigerants with …
Miniature Oil-Less Reciprocating Compressor For High-Lift, High-Temperature Heat Pump Applications, Daniel Lawrence Murphy, Michael S. Katancik
Miniature Oil-Less Reciprocating Compressor For High-Lift, High-Temperature Heat Pump Applications, Daniel Lawrence Murphy, Michael S. Katancik
International Compressor Engineering Conference
In the extreme temperature environment of the moon, the regolith surface temperature can reach 100°C during the 354-hour lunar day. This often exceeds the maximum allowable temperature of critical electronics onboard small lunar rovers designed for long-term science missions. In environments with such high heat sink temperatures, active vapor compression cooling solutions allow greater mission flexibility than traditional passive spacecraft thermal control. The objective of this research was to design and experimentally evaluate a critical enabling technology for effective lunar rover class heat pumps: the high-lift, high-temperature, microgravity compressor. The main technical challenges in the design of a compressor for …
Numerical Analysis And Optimization For Hydrodynamic Lubrication In Journal Bearings Of Rotary Compressor, Bing Yu, Ouxiang Yang, Jia Xu, Huijun Wei, Haihong Zhao
Numerical Analysis And Optimization For Hydrodynamic Lubrication In Journal Bearings Of Rotary Compressor, Bing Yu, Ouxiang Yang, Jia Xu, Huijun Wei, Haihong Zhao
International Compressor Engineering Conference
Based on the average Reynolds’ equation of hydrodynamic lubrication, the axis locus and the minimum oil film thickness of the journal bearings under the dynamic load were numerically solved in this paper, and the movement and bearing characteristics of the compressor bearings at different rotation speeds were analyzed to evaluate the influence of the friction loss of the journal bearings on the performance of the rotary compressor. The simulation results indicated that the minimum oil film thickness of the sub bearing is smaller than the critical oil film thickness at low rotation speed (n ≤ 1800 rpm), therefore, the friction …
Improving Lifetime Of Domestic Compressor Subjected To Repetitive Internal Stresses, Seongwoo Woo, Dennis O'Neal, Dereje Engida Woldemichael, Samson Mekbib Atnaw, Muluneh Mekonnen
Improving Lifetime Of Domestic Compressor Subjected To Repetitive Internal Stresses, Seongwoo Woo, Dennis O'Neal, Dereje Engida Woldemichael, Samson Mekbib Atnaw, Muluneh Mekonnen
International Compressor Engineering Conference
To enhance the lifetime of a mechanical system such as compressor, parametric accelerated life testing (ALT) as a systematic reliability method is proposed. It consists of (1) a parametric ALT plan formed on BX lifetime, (2) load examination for ALT, (3) a customized parametric ALTs with design alternatives, and (4) assessment of the compressor design to secure the objective BX lifetime is fulfilled. As an experiment instance, newly designed reciprocating compressors for French-door refrigerators returned from the marketplace were investigated. The refrigerators had been making disagreeable noise and vibrations, creating the consumer to ask for replacing their refrigerators. As the …
Theoretical Analysis Of Noise And Vibration Generated By Gas Pressure Pulsation In Hermetic Compressors, Dazhuang He, Davide Ziviani, Yangfan Liu
Theoretical Analysis Of Noise And Vibration Generated By Gas Pressure Pulsation In Hermetic Compressors, Dazhuang He, Davide Ziviani, Yangfan Liu
International Compressor Engineering Conference
Due to the intermittent nature of discharge flow in hermetic compressors, gas pulsation is a major source of noise, vibration and harshness (NVH) effects. In the presented study on gas pulsation noise of hermetic compressors, a model was developed where the thermodynamics aspects of the compression process and the vibro-acoustics aspects are coupled together. The vibro-acoustics submodel is based on finite element method, and it describes the two-way coupled interaction of compressor cavity acoustics and shell vibration. The thermodynamics submodel is based on compressor model developed in previous studies, PDSim. It is used to compute the discharge gas pulsations that …
Experimental And Numerical Analysis Of Reed Valve Movement In An Impact Fatigue Test System And Reciprocating Compressors, Muhammad Waqas Tofique, Alexander Löf, Eugenio Schillaci, Pablo Castrillo, Joaquim Rigola
Experimental And Numerical Analysis Of Reed Valve Movement In An Impact Fatigue Test System And Reciprocating Compressors, Muhammad Waqas Tofique, Alexander Löf, Eugenio Schillaci, Pablo Castrillo, Joaquim Rigola
International Compressor Engineering Conference
During operation of a reciprocating compressor, its flapper valve opens to allow the passage of gases and closes by striking against the valve impact plate. This reed valve movement and impact is repeated billions of times. This cyclic movement has a significant influence on the impact fatigue life of the reed valve and, hence, the lifetime of a compressor. Inside a reciprocating compressor, a number of parameters including: the valve design, valve material, compressor operating frequency and suction/exhaust pressure, influence the reed valve movement. The valve movement can be defined in terms of valve frequency, valve lift, valve velocity and …
A New Alloy For High Performance Valve Steel For High Efficiency Compressors, Anders Hoel, Jonas Nilsson, Stefan Jonsson, Guocai Chai, Guofan Zhang
A New Alloy For High Performance Valve Steel For High Efficiency Compressors, Anders Hoel, Jonas Nilsson, Stefan Jonsson, Guocai Chai, Guofan Zhang
International Compressor Engineering Conference
In 2018 the International Energy Association IEA reported that air conditioning will be a major contributor for future electricity consumption (Birol, F. 2018). As recently seen in China, tougher legislation on energy efficiency for air conditioning and refrigeration is being introduced all the time. It is therefore crucial that new compressor models perform at the highest levels in terms of efficiency to reduce global energy consumption. The prerequisites to fulfill this legislation vary for the different applications such as rotary, reciprocating, scroll and linear compressors. However, to succeed in developing more energy efficient compressors, the ability to improve the performance …
Characterization Of Oil Droplets In The Upper Cavity Of A Rotary Compressor, Puyuan Wu, Jun Chen, Paule. Sojka, Yang Li, Hongjun Cao
Characterization Of Oil Droplets In The Upper Cavity Of A Rotary Compressor, Puyuan Wu, Jun Chen, Paule. Sojka, Yang Li, Hongjun Cao
International Compressor Engineering Conference
The lubricant oil is used to lubricate the bearings and seal the clearance between the sliding parts in the rotary compressor equipped in an air conditioning system. However, a portion of the oil is atomized and exhausted with the refrigerant flow, which reduces the system’s efficiency and reliability. In this study, a highresolution shadowgraph system is applied to a modified rotary compressor to visualize the oil droplets in its upper cavity. The oil droplet size distribution is studied statistically at different radial locations and different crankshaft’s frequencies. It is observed that more oil droplets with larger D10 and D32 are …
Experimental Investigation Of An Optimized Mechanically Assisted Suction Reed Valve Of A Hermetic Reciprocating Compressor, Andreas Egger, Raimund Almbauer, Michael Lang, Christoph Zainer
Experimental Investigation Of An Optimized Mechanically Assisted Suction Reed Valve Of A Hermetic Reciprocating Compressor, Andreas Egger, Raimund Almbauer, Michael Lang, Christoph Zainer
International Compressor Engineering Conference
Reed valves are widely used in hermetic reciprocating compressors for domestic refrigeration. They are crucial components in terms of efficiency, cooling performance, noise and reliability of the compressor. While reed valves already cause a significant proportion of the thermodynamic losses in fixed speed compressors, they induce even more challenges in variable speed compressors. Especially in variable speed compressors, a further improvement of the reed valve dynamics requires the consideration of a new valve concept. In this work, a new design concept of a mechanically assisted suction valve is experimentally investigated. A mechanically actuated spiral spring generates a variable supporting force …
An Approach To Detach The Thermodynamic Losses Of A Reciprocating Compressor, Ernane Silva, Thiago Dutra
An Approach To Detach The Thermodynamic Losses Of A Reciprocating Compressor, Ernane Silva, Thiago Dutra
International Compressor Engineering Conference
Due to several incentives for reducing energy consumption worldwide, there is an increasingly demand for high-efficiency compressors for refrigeration systems. During the design stage of a refrigeration compressor, the designer needs to identify the main energy losses so as to propose alternatives to increase the compressor efficiency. The energy losses associated with the compression cycle are typically evaluated from the indicated diagram, which allows an accurate estimate of viscous flow losses through the suction and discharge systems, but no clear identification of piston-cylinder leakage and heat transfer losses. This paper presents a theoretical method to assess the energy losses associated …
Field Performance Of Domestic Heat Pumps For Heating And Hot Water In Switzerland Part I: Technology, Methods And State Of The Art Of The Field Studies, Ralph R. Kuster, Manuel Prinzing, Berthold Matthias, Mick Eschmann, Stefan S. Bertsch
Field Performance Of Domestic Heat Pumps For Heating And Hot Water In Switzerland Part I: Technology, Methods And State Of The Art Of The Field Studies, Ralph R. Kuster, Manuel Prinzing, Berthold Matthias, Mick Eschmann, Stefan S. Bertsch
International Refrigeration and Air Conditioning Conference
carried out by the Heat Pump Test Center (WPZ) in Buchs SG, Switzerland. In the current study, heat pumps for hydronic heating systems in single family houses within Switzerland have been investigated since 2016. So far, over 20 air-source and geothermal heat pumps have been added to this governmental quality assurance program (Swiss Federal authority EnergieSchweiz). For each heat pump system, more than 40 measured variables are recorded at a time interval of 10 s with calibrated sensors with very low measurement uncertainty. The aim of this field study is to record the real heat pump system efficiency in operation …
Influence Of The Refrigerant Maldistribution In The Performance Of Brazed Plate Heat Exchangers Working With Propane, Emilio Navarro-Peris, Lucas Alvarez, Paloma Albaladejo, Lena Schnabel, Jose M Corberan
Influence Of The Refrigerant Maldistribution In The Performance Of Brazed Plate Heat Exchangers Working With Propane, Emilio Navarro-Peris, Lucas Alvarez, Paloma Albaladejo, Lena Schnabel, Jose M Corberan
International Refrigeration and Air Conditioning Conference
Brazed plate heat exchangers (BPHE) are used widely in heating and cooling systems, mainly for liquid-to-liquid heat transfer but also for two-phase-applications like evaporation and condensation. Using them as evaporator or condenser in a heat pump the proper performance of them strongly influences the energy efficiency of the cycle and the required amount of refrigerant. One of the most common factors affecting the performance of BPHE is the not uniform distribution of the refrigerant. This problem is especially important in the evaporator as the refrigerant enters in it in two phase flow and usually the distribution of liquid and vapor …
Implementation Of Innovative Measurement Techniques For Precise Experimental Characterization Of Frost Growth In A Heat Pump Evaporator, Antoine Parthoens, Samuel Gendebien, Vincent Lemort
Implementation Of Innovative Measurement Techniques For Precise Experimental Characterization Of Frost Growth In A Heat Pump Evaporator, Antoine Parthoens, Samuel Gendebien, Vincent Lemort
International Refrigeration and Air Conditioning Conference
Refrigeration systems such as heat pumps may be subject to frost formation due to ambient air humidity. This phenomenon plays a major role in the HP overall performance drop due to the presence of an additional thermal resistance and an increase of the air-side pressure drop. The aim of this paper is to present a new innovative experimental technique to measure the amount of frost (or condensates) within the evaporator and therefore the air latent load. As the refrigerant distribution may vary with the frost apparition at the evaporator level, the exchanger cannot be weighted on its own to measure …
Validation Of A Load-Based Testing Method For Characterizing Residential Air-Conditioner Performance, Parveen Dhillon, Drew Welch, Brian Butler, W. Travis Horton, James E. Braun
Validation Of A Load-Based Testing Method For Characterizing Residential Air-Conditioner Performance, Parveen Dhillon, Drew Welch, Brian Butler, W. Travis Horton, James E. Braun
International Refrigeration and Air Conditioning Conference
Seasonal performance assessments of air-conditioning and heat-pump systems are typically carried out based on performance measurement of equipment in a test laboratory. The performance ratings that arise from these assessments are important in providing information to consumers, and in influencing policymakers to determine appropriate incentives for high-efficiency equipment in the marketplace. The current testing and rating approach for performance evaluation of residential air-conditioning and heat-pump systems is based on steady-state performance measurements, with a degradation coefficient to account for the cycling losses that occur during part-load operating conditions. However, this current methodology fails to appropriately characterize the true performance characteristics …
Theoretical Analysis Of Rigid-Body Vibration In Swing Compressors, Daiki Kikutake, Tatsuya Katayama, Hideki Matsuura
Theoretical Analysis Of Rigid-Body Vibration In Swing Compressors, Daiki Kikutake, Tatsuya Katayama, Hideki Matsuura
International Compressor Engineering Conference
This study aims to theoretically analyze the rigid-body vibration in swing compressors. Currently, low noise and vibration (NV) are qualities recognized as a desired value for an air conditioner by end users. Because the compressor is one of the main sources of NV in an air conditioner, low NV compressors are needed. Designing a low NV compressor requires the understanding of the physical phenomena occurring in a compressor that contribute to NV. In this study, we theoretically analyzed rigid-body vibration, which has been one of the main phenomena causing NV in a swing compressor. Main factors causing rigid-body vibration in …
Restart Test Design For Inverter Compressors, Tugba Cetinturk, Bilgin Hacioglu
Restart Test Design For Inverter Compressors, Tugba Cetinturk, Bilgin Hacioglu
International Compressor Engineering Conference
When a short power cut or electricity failure occurs on an electric supply system, which the household refrigerator is connected to, the suction and discharge pressures of the system become unbalanced, and the compressor exposes to higher loads than rated conditions. If the power recovers very quickly before the pressures get balanced, the compressor may not overcome the load and fails to start up. If the inverter control of the compressor has Class B protection software instead of mechanical overload protector; the inverter software forms a fault signal, cuts the energy through the compressor and waits for a while that …
Simulation-Based Energy And Daylighting Impact Assessment Of Integrated Shading Devices And Lighting Controls In Commercial Buildings, Niraj Kunwar, Mahabir Singh Bhandari
Simulation-Based Energy And Daylighting Impact Assessment Of Integrated Shading Devices And Lighting Controls In Commercial Buildings, Niraj Kunwar, Mahabir Singh Bhandari
International High Performance Buildings Conference
Fenestration systems are estimated to be responsible for 1,790 PJ of primary energy consumption annually in commercial buildings in the US and have significant impact on occupants’ visual and thermal comfort. Window shading devices such as shades and blinds are cost-effective means to reduce energy losses/gains from fenestration systems and provide a comfortable environment in the buildings. Besides being cost effective, these products are less intrusive to install when retrofitting the buildings. To maximize the benefits, however, these products require integrated control strategies. Due to complex modeling process involved, existing control strategies used by shade automation industries, generally are not …
A Comparison Of Interpolation Methods In Fast Fluid Dynamics, Eric Leonard, Hongtao Qiao, Saleh Nabi
A Comparison Of Interpolation Methods In Fast Fluid Dynamics, Eric Leonard, Hongtao Qiao, Saleh Nabi
International High Performance Buildings Conference
This paper examines the use of OpenFOAM’s cellPoint and cellPointWallModified interpolation routines in fast fluid dynamics (FFD). In addition, an arrangement of OpenFOAM’s data structures is proposed which speeds up FFD and an adjustment to FFD which incorporates the Boussinesq approximation is discussed. The findings of this paper show that the use of the cellPointWallModified interpolation routine in FFD produces results closer to reference data in higher Reynolds number flows than the use of the cellPoint interpolation routine, a result which highlights the important role that interpolation plays in the accuracy of FFD.
3d Cfd Simulation Of A New Ventilated Roof, Michele Calati, Luca Doretti, Cristiano Gatto, Simone Mancin
3d Cfd Simulation Of A New Ventilated Roof, Michele Calati, Luca Doretti, Cristiano Gatto, Simone Mancin
International High Performance Buildings Conference
In the last decades, energy management and saving have become challenging issues. Considering the building sector (residential or industrial), different technologies have been developed in order to realize tangible energy savings, such as: ventilated roof, double facades, glazed surfaces, etc. Nonetheless, it is important for these new technologies to contemporary assure the human thermal comfort. Passive cooling (or heating) technologies are of actual interest. Low or near-zero energy buildings can only be realized as a result of the good design of all their components; specifically, the roofs call for particular attention as they take large parts of a building’s total …
Design And Development Of A Human Building Interaction Laboratory, Sourabh Yadav, Parveen Dhillon, Orkan Kurtulus, Charles Baxter, Davide Ziviani, W Travis Horton, Panagiota Karava, James E. Braun
Design And Development Of A Human Building Interaction Laboratory, Sourabh Yadav, Parveen Dhillon, Orkan Kurtulus, Charles Baxter, Davide Ziviani, W Travis Horton, Panagiota Karava, James E. Braun
International High Performance Buildings Conference
A future is envisioned where buildings are assembled on-site from factory manufactured modular elements that integrate the smart technology needed to enable scalable, cost-effective solutions with autonomous, occupant-responsive, healthy, and sustainable features. The use of modular elements would mean that buildings are assembled rather than constructed on-site with better quality control, less material waste, and more predictable schedules. The use of manufactured building elements can enable more cost-effective integration of new sensors, embedded intelligence, networking, adaptive interfaces, renewable energy, energy recovery, comfort delivery, and resiliency technologies, making high-performance buildings more affordable. To explore and evaluate these modular and intelligent comfort …
Performance Evaluation Of Three Virtual Metering Methods To Estimate Zone-Level Perimeter Heater Energy Requirement, Darwish Darwazeh, Jean Duquette, Burak Gunay
Performance Evaluation Of Three Virtual Metering Methods To Estimate Zone-Level Perimeter Heater Energy Requirement, Darwish Darwazeh, Jean Duquette, Burak Gunay
International High Performance Buildings Conference
Virtual metering provides a cost-effective alternative to physical meters to monitor building energy performance and capture unmetered energy flows at the zone-level. Virtual metering accuracy depends on the modelling method and its ability to represent the heating and cooling processes at a building thermal zone. This paper employs three virtual metering methods to estimate the heating energy of zone-level perimeter heaters: a steady-state modelling method, a transient modelling method, and a load disaggregation modelling method. Inverse models representing these three virtual metering methods are trained using data obtained from seven perimeter offices in an academic building in Ottawa, Canada. Model …
Standard Testing Protocols For Co2 Sensors And Co2-Based Demand Control Ventilation Systems, Antonea Frasier, Frederick Meyers, Derrick Ross, Theresa Pistochini, Matthew J. Ellis
Standard Testing Protocols For Co2 Sensors And Co2-Based Demand Control Ventilation Systems, Antonea Frasier, Frederick Meyers, Derrick Ross, Theresa Pistochini, Matthew J. Ellis
International High Performance Buildings Conference
No abstract provided.
Development And Evaluation Of Low-Cost Co2 Sensors For Buildings, Zachary A. Siefker, Abhi R. Boyina, Xikang Zhao, John N. Hodul, James E. Braun, George T C Chiu, Bryan W. Boudouris, Jeffrey F. Rhoads
Development And Evaluation Of Low-Cost Co2 Sensors For Buildings, Zachary A. Siefker, Abhi R. Boyina, Xikang Zhao, John N. Hodul, James E. Braun, George T C Chiu, Bryan W. Boudouris, Jeffrey F. Rhoads
International High Performance Buildings Conference
There is a significant opportunity to improve building energy efficiency and indoor environmental quality by accurately monitoring CO2 levels. However, current CO2 sensors tend to be expensive or require regular recalibration. This work presents research related to the initial development and evaluation of two novel CO2 sensors based on chemiresistive and resonant mass sensing techniques. Prototype sensors were assessed in a bench-top test chamber at temperatures, humidity levels, and CO2 concentrations, typical of indoor environments. Under these conditions, prototype sensors required only 60 mW of power, or less. Further, each sensor was developed to have a footprint of less than …
Environmental Index For Real Time Feedback On Biowall Indoor Air Quality, William Hutzel, Hengyu Liu, Jun Ho Kim
Environmental Index For Real Time Feedback On Biowall Indoor Air Quality, William Hutzel, Hengyu Liu, Jun Ho Kim
International High Performance Buildings Conference
This paper describes an ongoing field evaluation of a simplified Environmental Index (EI) that provides a homeowner with an intuitive metric for assessing indoor air quality based on regular measurements of temperature, humidity, and Volatile Organic Compounds (VOC’s). These discrete measurements are used to compute an overall weighted score that correlates with the comfort and health of the living space. Although this environmental index is not a rigorous scientific computation, it is an initial point to improve residents’ understanding of Indoor Air Quality (IAQ) by providing active feedback. The context of this environmental index work is the Biowall, a living …
Characteristics Of Graphite And Mno2 Enhanced Cement-Based Thermoelectric Composite For Low-Temperature Applications, Xiaoli Liu, Ming(1) Qu, Alan Phong Tran Nguyen
Characteristics Of Graphite And Mno2 Enhanced Cement-Based Thermoelectric Composite For Low-Temperature Applications, Xiaoli Liu, Ming(1) Qu, Alan Phong Tran Nguyen
International High Performance Buildings Conference
Thermoelectric (TE) cement composite is a new type of TE material. Unlike ordinary cement, TE cement can mutually convert thermal energy to electrical energy due to the addition of carbon fibers, metal oxide nanoparticles, etc. In hot summer or cold winter, the significant temperature difference between indoor and outdoor can be used by TE cement to generate electricity. On the other hand, given power input, the same material can provide cooling/ heating to adjust room temperature. Therefore, TE cement has certain energy-saving potential in the application of building enclosures and energy systems. Its ability to convert different forms of energy …
Force Failure Dielectric Test Design For Stators Of Inverter Compressors, Tugba Cetinturk
Force Failure Dielectric Test Design For Stators Of Inverter Compressors, Tugba Cetinturk
International Compressor Engineering Conference
(PMAC) Electric motor is used at Variable Speed Refrigeration Compressors. Stator is the stationary part of a PMAC motor and stator wires directly carry the current, which energizes the motor and runs the refrigerator compressors. These wires are wound on stator stack which is made of electrical steel. The windings can be also close to other metal parts of the compressor. Stator stack is connected to compressor metal parts by metal screws. So, if a leakage current occurs through the stator stack, it is directly conveyed to compressor housing and then to refrigerator which can cause electric shock on the …
Field Performance Of Domestic Heat Pumps For Heating And Hot Water In Switzerland Part Ii: Results, Analysis And Optimization, Ralph R. Kuster, Manuel Prinzing, Berthold Matthias, Mick Eschmann, Stefan S. Bertsch
Field Performance Of Domestic Heat Pumps For Heating And Hot Water In Switzerland Part Ii: Results, Analysis And Optimization, Ralph R. Kuster, Manuel Prinzing, Berthold Matthias, Mick Eschmann, Stefan S. Bertsch
International Refrigeration and Air Conditioning Conference
This study presents the development, the methods, and the state of the art of heat pump field trials as they are currently carried out by the Heat Pump Test Center (WPZ) in Buchs SG, Switzerland. In the current study, heat pumps for hydronic heating systems in single family houses within Switzerland have been investigated since 2016. So far, over 20 air-source and geothermal heat pumps have been added to this governmental quality assurance program (Swiss Federal authority EnergieSchweiz). For each heat pump system, more than 40 measured variables are recorded at a time interval of 10 s using calibrated sensors …
Application Of A Color Change Coating To Evaluate Flow Velocity Distribution And Wall Shear Stress Of Fan Blade, Min Che, Stefan Elbel
Application Of A Color Change Coating To Evaluate Flow Velocity Distribution And Wall Shear Stress Of Fan Blade, Min Che, Stefan Elbel
International Refrigeration and Air Conditioning Conference
A mass transfer method has been employed to characterize tangential flow velocity around fan blades. In the current research, two commercial air-conditioning fan blade samples have been investigated. The blade surfaces were covered with a 10 μm yellow coating by a spray method. The fan and a camera are driven by a motor and shaft system that can synchronize the rotational speed. Therefore, a relative stay still image of the fan blade during rotation can be obtained. Subsequently, a small amount (50 ppmv) of ammonia has been injected into an environmental chamber that has the fan installed and rotating. The …
Review Of Humidity Effect On Humid Air-To-Water Condensation By A Cooling Surface For Atmospheric Water Harvesting, Gyeong Sung Kim, Tao Cao, Yunho Hwang
Review Of Humidity Effect On Humid Air-To-Water Condensation By A Cooling Surface For Atmospheric Water Harvesting, Gyeong Sung Kim, Tao Cao, Yunho Hwang
International Refrigeration and Air Conditioning Conference
Many atmospheric water harvesting technologies have been produced to mitigate water scarcity as an auxiliary source of water. These technologies may be described as direct and indirect water collection techniques. The direct method is to induce a phase-change turning from vapor to liquid on a cooling surface and generate condensate without interim processes. On the other hand, the indirect method has absorption or adsorption processes to take water from humid air before producing water. This paper focuses on the direct methods and discusses the effects of humidity and surface temperature on water generation rates and condensate droplet formation patterns in …
The Performance Of An Automotive Carbon Dioxide Heat Pump System In Frosting And Defrosting, Wenying Zhang, Pega Hrnjak
The Performance Of An Automotive Carbon Dioxide Heat Pump System In Frosting And Defrosting, Wenying Zhang, Pega Hrnjak
International Refrigeration and Air Conditioning Conference
This paper presents the performance in frosting and defrosting of an automotive carbon dioxide (CO2) heat pump system, which is composed of a microchannel indoor and outdoor coil, a reciprocating compressor, an electronic expansion valve, and an integrated accumulator and internal heat exchanger. The effects of the criterion for the start of defrosting on the heat pump system performance were investigated experimentally. The defrost-start criterion was determined based on the reduction in the performance of the heat pump system instead of only considering the performance of the outdoor coil. Results show the heat pump system can operate for 64 minutes …