scholarly journals Subcritical and Supercritical Operation of Innovative Thermal Mechanical Refrigeration System

2020 ◽  
Author(s):  
Ahmad Sleiti ◽  
Wahib Al-Ammari ◽  
Mohammed Al-Khawaja ◽  
Maxim Glushenkov ◽  
Alexander Kronberg
Keyword(s):  
Global Warming ◽  
Ozone Depletion ◽  
Fossil Fuels ◽  
Waste Heat ◽  
Low Frequency ◽  
Low Grade ◽  
Refrigeration System ◽  
Heat System ◽  
Global Warming Potentials ◽  
Carbon Dioxide Co2

Around 17% of the globally generated energy is consumed for residential, commercial, and transportation refrigeration. The current cooling technologies utilize refrigerants with high Ozone Depletion and Global Warming Potentials. Furthermore, the current technologies are expensive alongside with toxicity and flammability hazards. On the other side, energy produced by combustion of fossil fuels results in substantial amounts of waste heat. Therefore, it is necessary to develop new refrigeration technologies that utilize waste heat as a source of energy with ecofriendly refrigerants with zero ozone depletion potential and zero global warming potential. In addition, this thermal mechanical refrigeration (TMR) technology improves the energy efficiency of the source of waste heat system and minimizes the emissions of the carbon dioxide (CO2). In this study, a novel thermo-mechanical refrigeration system is proposed. It operates with low-grade energy sources (such as waste heat) at temperature range of 60 oC to 100 oC. Furthermore, it has the advantage of working with low-frequency driver-compressor unit, which eliminates noise and increases its lifetime. Moreover, the TMR system is adaptable to commercial, transportation, and residential refrigeration applications.

REVIEW ON EJECTOR OF VAPOR JET REFRIGERATION SYSTEM

2014 ◽  
Vol 22 (03) ◽  
pp. 1430003 ◽  
Author(s):  
PARVEEN BANU JIAUTHEEN ◽  
MANI ANNAMALAI
Keyword(s):  
Performance Improvement ◽  
Fossil Fuels ◽  
Performance Enhancement ◽  
Waste Heat ◽  
Experimental Studies ◽  
Low Grade ◽  
Vapor Compression ◽  
Refrigeration System ◽  
Two Phase ◽  
Developmental Progress

Vapor Jet Refrigeration (VJR) system is attractive among various heat operated refrigeration systems, because it has the potential of utilizing low grade thermal energy with source temperature as low as 60°C, which could be harnessed from renewable energy, waste heat, automobile-exhaust, etc. Also absence of moving parts in this system resulted in lesser maintenance costs. In addition to that this system causes very low environmental pollution due to almost negligible consumption of high grade energy from fossil fuels for running a small liquid pump of the system. Although VJR was invented very long back, still performance improvement to compete with vapor compression refrigeration system is in progress. Plenty of research has been carried out in different aspects for enhancing the efficiency of this technology. The present work/paper gives an overview of VJR system and its progression in the aspect of performance improvement. The developmental progress of the VJR technology presented in this paper has been categorized into the following groups, namely (a) general performance of an ejector, (b) numerical analysis, viz., classical one-dimensional analysis and Computational Fluid Dynamics (CFD) analysis, (c) experimental studies, (d) flow visualization studies, (e) performance enhancement techniques, and (f) two-phase ejector. And also presented a glimpse of some of the review papers from literature on VJR system.

Review of Technology Used to Improve Heat and Mass Transfer Characteristics of Adsorption Refrigeration System

2016 ◽  
Vol 24 (02) ◽  
pp. 1630003 ◽  
Author(s):  
Anirban Sur ◽  
Randip K. Das
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Waste Heat ◽  
Transfer Characteristic ◽  
Low Grade ◽  
Transfer Performance ◽  
Refrigeration System ◽  
Adsorption Refrigeration ◽  
System A ◽  
Absorption Refrigeration System

Researchers proved that, heat powered adsorption refrigeration technology is very effective methods for reutilization of low-grade thermal energy such as industrial waste heat, solar energy, and exhaust gases from engines. But to make it commercially competitive with the well-known vapor compression and absorption refrigeration system, the processes require high rates of heat and mass transfer characteristic between adsorbate and adsorbent as well as externally supplied heat exchanging fluid. This paper reviews various techniques that have been developed and applied to enhance the heat transfer and mass transfer in adsorber beds, and also discuss their effects of the performance on adsorption system. A comprehensive literature review has been conducted and it was concluded that this technology, although attractive, has limitations regarding its heat and mass transfer performance that seem difficult to overcome. Therefore, more researches are required to improve heat and mass transfer performance and sustainability of basic adsorption cycles.

Environment Friendly Mixed Refrigerant to Replace R-134a in a VCR System with Exergy Analysis

2014 ◽  
Vol 984-985 ◽  
pp. 1174-1179
Author(s):  
N. Austin ◽  
P.M. Diaz ◽  
D.S. Manoj Abraham ◽  
N. Kanthavelkumaran
Keyword(s):  
Global Warming ◽  
Global Warming Potential ◽  
Ozone Depletion ◽  
Exergy Analysis ◽  
Coefficient Of Performance ◽  
Refrigeration System ◽  
Evaporator Temperature ◽  
Environment Friendly ◽  
A Charge ◽  
Vapour Compression

Study on environment friendly mixed refrigerant to replace R134a in vapour compression refrigeration (VCR) System. The mixed refrigerants investigated are propane (R290), butane (R600), isobutene (R600a) and R134a. Even though the ozone depletion potentials of R134a relative to CFC-11 are very low; the global warming potentials are extremely high and also expensive. For this reason, the production and use of R134a will be terminated in the near future. Hydrocarbons are free from ozone depletion potential and have negligible global warming potential. The results showed that, mixed refrigerant with charge of 80 g satisfy the required freezer air temperature when R134a with a charge of 110 g is used as refrigerant. The actual COP of refrigerator using mixed refrigerant was almost nearer that of the system using R134a as refrigerant. The coefficient of performance of the vapour compression refrigeration system using mixed refrigerant MR-3 [R134a/R290/ R600a/ R600 (20/35/40/5)] is having very close value with R134a and the Global warming potential of MR-3 is negligible when compared with R134a. Hence the mixed refrigerant MR-3 is chosen as an environmental friendly alternate refrigerant to R134a. The exergy analysis of the vapour compression refrigeration system using R134a and all the above mixtures are investigated. The effect of evaporator temperature on exergy efficiency and exergy destruction ratio of the system are experimentally studied. The exergy defect in the compressor, condenser, expansion device and evaporator are also obtained. Key words: R134a, Mixed refrigerant, Chlorofluorocarbons, Propane, Butane, Isobutene, REFPROP, COP, ODP, GWP, Exergy, VCR System.

scholarly journals Performance Analysis of Vapour Compression Refrigeration System using HC Refrigerant Mixtures for Water Chiller

2019 ◽  
Vol 8 (9) ◽  
pp. 2513-2517
Keyword(s):  
Global Warming ◽  
Performance Analysis ◽  
Ozone Depletion ◽  
Operating Conditions ◽  
Superior Performance ◽  
Refrigeration System ◽  
Refrigerant Mixture ◽  
Refrigerant Mixtures ◽  
Vapour Compression ◽  
Hfc Refrigerant

The use of HC refrigerant mixtures has been a topic of current research in view of the concerns related to global warming and Ozone depletion problems caused by CFCs and HFCs.. The HC mixture as an alternate refrigerant has been reported to be a promising one in addressing the global warming and Ozone depletion problems. In the present work an experimental set-up is built up to test Vapour Compression Refrigeration (VCR) system with different refrigerants. The aim of this work is to investigate the performance analysis of Vapor Compression Refrigeration system with alternate refrigerants such as Hydrocarbon (HC) refrigerants mixture and compare with Hydro Fluoro Carbon (HFC) refrigerant (R134a) under the similar operating conditions. The alternate refrigerant mixture is selected in the combination of Propane (R290) and Iso-butane (R600a). The refrigeration system variables considered for the investigation of performance are evaporating temperature, condensing temperature and power consumption. The HC refrigerant mixture is observed to give superior performance compared to HFC refrigerant in terms of global warming.

scholarly journals Developments of the Perception of Climate Change and Abnormal Weather in Postwar Japan

2021 ◽  
Author(s):  
Keegan Cothern ◽  
Junichi Hasegawa
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Ozone Depletion ◽  
Climatic Variability ◽  
Climate Research ◽  
Postwar Japan ◽  
Global Cooling ◽  
Carbon Dioxide Co2 ◽  
Abnormal Weather

Climate research has been presented as a largely Anglophone and European affair, while other regional contributions and concerns have been left largely unexamined. An investigation of the Japan Meteorological Agency’s ‘Abnormal Weather Reports’ and related literature instead reveals the concerns of an island nation anxious about immediate weather abnormalities, causes of climate variability, and predicting the consequences of global warming within a geographically vulnerable Japan. Researchers initially focused on the topic of global cooling in the 1970s, sparking fears about Japan’s self-sustainability in the event of a long-term decline in temperatures. By the 1980s, though cooling fears persisted, focus also turned to how El Niño cycles provoked climatic variability, even as initial concern with global warming resulting from human activities, carbon dioxide (CO2) emissions, and ozone depletion grew. Following the Kyoto Protocol’s recognition of anthropogenic climate change and creation of a global cooperative framework, research has begun to focus on the consequences of global warming in exacerbating Japan’s meteorological risks and on mitigating further anthropogenic temperature increases.

Mental Models and Risk Perceptions Related to Climate Change

2017 ◽  
Author(s):  
Ann Bostrom
Keyword(s):  
Climate Change ◽  
Air Pollution ◽  
Global Warming ◽  
Mental Models ◽  
Ozone Depletion ◽  
Mental Model ◽  
Risk Perceptions ◽  
Fossil Fuels ◽  
Stratospheric Ozone ◽  
Stratospheric Ozone Depletion

Mental models are the sets of causal beliefs we “run” in our minds to infer what will happen in a given event or situation. Mental models, like other models, are useful simplifications most of the time. They can, however, lead to mistaken or misleading inferences, for example, if the analogies that inform them are misleading in some regard. The coherence and consistency of mental models a person employs to solve a given problem are a function of that person’s expertise. The less familiar and central a problem is, the less coherent and consistent the mental models brought to bear on that problem are likely to be. For problems such as those posed by anthropogenic climate change, most people are likely to recruit multiple mental models to make judgments and decisions. Common types of mental models of climate change and global warming include: (a) a carbon emissions model, in which global warming is a result of burning fossil fuels thereby emitting CO2, and of deforestation, which both releases sequestered CO2 and decreases the possible sinks that might take CO2 out of the atmosphere; (b) a stratospheric ozone depletion mental model, which conflates stratospheric ozone depletion with global warming; (c) an air pollution mental model, in which global warming is viewed as air pollution; and (d) a weather change model, in which weather and climate are conflated. As social discourse around global warming and climate change has increased, mental models of climate change have become more complex, although not always more coherent. One such complexity is the belief that climate changes according to natural cycles and due to factors beyond human control, in addition to changes resulting from human activities such as burning fossil fuels and releasing other greenhouse gases. As our inference engines, mental models play a central role in problem solving and subjective projections and are hence at the heart of risk perceptions and risk decision-making. However, both perceiving and making decisions about climate change and the risks thereof are affective and social processes foremost.

A Computer Program for Working Fluid Selection of Low Temperature Organic Rankine Cycle

2015 ◽  
Author(s):  
Muhammad Ansab Ali ◽  
Tariq Saeed Khan ◽  
Ebrahim Al Hajri ◽  
Zahid H. Ayub
Keyword(s):  
Low Temperature ◽  
Heat Source ◽  
Computer Program ◽  
Fossil Fuels ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Power Production ◽  
Working Fluid ◽  
Low Grade

Fossil fuels are continuously depleting while the global energy demand is growing at a fast rate. Additionally, fossil fuels based power plants contribute to environmental pollution. Search for alternate energy resources and use of industrial waste heat for power production are attractive topics of interest these days. One way of enhancing power production and decreasing the environmental impact is by recuperating and utilizing low grade thermal energy. In recent years, research on use of organic Rankine cycle (ORC) has gained popularity as a promising technology for conversion of heat into useful work or electricity. Due to simple structure of ORC system, it can be easily integrated with any energy source like geothermal energy, solar energy and waste heat. A computer program has been developed in engineering equation solver (EES) environment that analyzes and selects appropriate working fluid for organic Rankine cycle design based on available heat sources. For a given heat source, the program compares energy and exergy performance of various working fluids. The program also includes recuperator performance analysis and compares its effectiveness on the overall thermal performance of the Rankine cycle. This program can assist in preliminary design of ORC with respect to best performing refrigerant fluid selection for the given low temperature heat source.

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