Low Ozone Depletion Potential Research Articles

Methods of Improving Thermal Performance of Vapour Compression Based Refrigeration System Through Eco Friendly Refrigerants to Reduce Their Environmental Impact

Tetrafluoroethane (CF3CH2F), an HFC refrigerant, is also known as R134a. It is safe for normal handling because it is neither poisonous, flammable, nor corrosive. After it was discovered recently that R-134a contributes to global warming, the European Union forbade its use in brand-new automobiles starting in 2011. Worked on a vapour compression-based refrigeration system, utilised hydrocarbon (HC) refrigerants which were examined for their energetic and exergetic performance. In this investigation, pure Tetrafluoroethane (CF3CH2F) from the R134a family of HFCs was used for a theoretical analysis, along with other refrigerants which were eco-friendly and had a lower environmental impact( low Global Warming Potential and Ozone Depletion Potential) :trans-1,3,3,3- Tetrafluoroprop -1-ene( R1234 ze (Z), R1234ze (E), (Z)-1-Chloro-2,3,3,3-Tetrafluoropropane (R1224YD (Z)), Fluoroethene (R1141),3,3,3-Trifluoroprop-1-ene (R1243 ZF).The thermodynamic equations of the refrigerants were solved for analysis using the Engineering equation solver application. It was concluded that R1234ZE (Z) is the most effective refrigerant.

Organic Rankine cycle-ejector heat pump hybrid system using low GWP zeotropic mixtures for trigeneration application

This paper presents a comprehensive study focused on improving the thermal efficiency and performance of an organic Rankine cycle (ORC) combined with an ejector heat pump (EHP) for trigeneration application. The utilization of zeotropic mixtures with low global warming potential (GWP) was proposed as a solution to address the inherent inefficiencies of the ORC at low-temperature heat sources and to enhance the coefficient of performance (COP) of the ejector refrigeration cycle. A thermodynamic model was developed to predict system performance, utilizing low-temperature heat sources such as solar or geothermal energy, along with zeotropic mixtures. The model was validated with the available literature data, demonstrating very good agreement. Five zeotropic fluid mixtures were preliminary studied, and the optimal mass fractions identified. Detailed investigations were then carried out for two of these mixtures, R1233zd(E)/propane and butane/propane, which exhibit low GWP and ozone depletion potential (ODP). The influence of generator temperature and entrainment ratio on system efficiency metrics, exergy, and COP were evaluated for these mixtures. Conclusions are drawn based on the two optimized zeotropic mixtures for maximum thermal efficiency. For R1233zd(E)/propane mixture with mass fractions 0.75/0.25 and butane/propane mixture with mass fractions 0.5/0.5 at generator temperature of 75 °C and entrainment ratio of 0.5, the systems achieved a heating capacity of 1607.9 kW and 2847.9 kW, a cooling capacity of 1037.5 kW and 1280.3 kW, and a net power output of 59.2 kW and 136.3 kW. Other related performance and efficiency parameters are included in the paper. These findings indicate the feasibility of utilizing these systems for trigeneration application. Additionally, a comparative analysis with a regenerative ORC highlighted the ORC-EHP hybrid system's advantages, including enhanced heating efficiency, cooling capacity, and overall COP.This research contributes valuable insights to advance the efficiency and sustainability of combined cooling, heat, and power systems, fostering the progression of innovative energy solutions.

Influence of Long-Term Storage and UV Light Exposure on Characteristics of Polyurethane Foams for Cryogenic Insulation.

Rigid polyurethane (PUR) foams have been the most effective insulation material used in space launchers since the beginning of cryogenic fuel use, due to their outstanding thermal and mechanical properties. In this study, spray-applied PUR foams using different ratios of amine-based catalysts were produced. Due to climate change, several restrictions have been made regarding the usage of blowing agents used for PUR foam production. Lately, hydrofluoroolefins (HFOs) have been suggested as an alternative for PUR foam production due to their low global warming potential (GWP) and ozone depletion potential (ODP), replacing the hydrofluorocarbons (HFCs) so far used. This change in blowing agents naturally altered the usage of catalysts. Reactive amine-based catalysts are less hazardous because of their low volatility and ability to react successfully with isocyanate or polyols. Spray-applied PUR foams with a potential application for cryogenic insulation were produced and tested for long-term storage, analyzing parameters such as the pH value of polyol composition, foaming kinetics (trise, tcream), etc. Athermal analysis (TG, DSC) was also applied to developed materials, as well as artificial ageing by exposing samples to UV light. It was discovered that PUR foams obtained using reactive amine-based catalysts, such as Polycat 203 and 218, have a higher integral heat capacity, but polyol mixtures containing these catalysts cannot exceed a storage time of more than 4 months. It was also observed from artificial ageing tests of PUR cryogenic insulation by exposure to UV light that the thickness of the degraded layer reached 0.8 mm (after 1000 h), but no significant destruction of cellular structure deeper in the material was observed.

Investigative comparison of R134a, R290, R600a and R152a refrigerants in conventional vapor compression refrigeration system

This work represents the performance comparison of conventional vapour compression refrigeration system (VCRS) using various refrigerants such as R134a, R152a, R600a and R290. The theoretical model has been utilized for computing work input to the compressor, refrigerating effect and coefficient of performance (COP) for R134a, R290, R600a and R152a refrigerants. This investigation has been done for the evaporator temperature range of -30 °C to 10 °C and the condenser temperature range of 40 °C to 45 °C. In this performance analysis it is seen that R290 shows favourable properties and can serve as best refrigerant among all in the group. R290 shows almost equal COP to R600a in large operating temperature range and it has very high refrigerating capacity comparatively to R134a together with its low global warming potential and ozone depletion potential. R152a and R600a also show some satisfying properties.

Working fluid selection for a high efficiency integrated power/cooling system combining an organic Rankine cycle and vapor compression-absorption cycles

This paper presents the performance evaluation of several combinations of working fluids for a new heat recovery cogeneration system which combines an Organic Rankine Cycle (ORC), a Vapor Absorption Cycle (VAC) and a Vapor Compression Cycle (VCC). NH3–NaSCN is chosen as the working fluid in the VAC. Seven different refrigerants in the ORC-VCC were studied to identify the fluid that would allow the overall system to achieve a high efficiency in the tropical region. These fluids were chosen because of their low Global Warming Potential and Ozone Depletion Potential. A thermodynamic simulation allowed to set the appropriate operating conditions of the VAC. Subsequently, energy and exergy analyses showed that R717 is the appropriate working fluid for system operation in the tropical region. For this fluid, the highest values of cooling capacity, net power output, thermal efficiency, exergy efficiency and exergy destruction of the system were respectively 1205 kW, 158.3 kW, 64.32%, 39.39% and 690.4 kW for VCC evaporation temperature of 15 °C, for ORC-VCC condensation temperature of 40 °C and for ORC steam generator outlet temperature of 219.7 °C. The most exergy-destroying components are the steam generator and the ORC/VCC condenser with 57.29% and 22.58%, respectively.

Thermodynamic analysis of exhaust heat recovery of marine ice using organic rankine cycle

The use of organic Rankine cycle power systems for waste heat recovery on marine internal combustion engines can help to mitigate the GHG and reduce the fuel consumption of the marine engine. In this paper, the internal combustion engine combined with an organic Rankine cycle system was developed to analyze the performance of waste heat recovery from the exhaust gas of a heavy-duty marine Diesel engine via five selected working fluids with low global warming potential and ozone depletion potential. The net output power and thermal efficiency for each of the selected working fluids were obtained. Results indicate that the working fluids of butane have the best performance among the selected working fluids with the power efficiency of the organic Rankine cycle subsystem of 12.27% under the power load of 100%. For the overall proposed system, the maximum net power output is 1048 kW and the power efficiency is 36.47%. Besides, the total thermal efficiency of the proposed system was 67.94% when considering the recovered waste energy from jacket water.

Fire suppression using trifluoroiodomethane (CF3I)-carbon dioxide (CO2) mixtures

With the regulatory prohibition for using Halon 1301 (CF3Br) in fire suppression systems onboard newly certified aircraft, significant research efforts have been undertaken to develop suitable halon replacements with comparable suppression performance that are also eco-friendly with low Ozone Depletion Potential (ODP) and Global Warming Potential (GWP). This paper determined the fire suppression effectiveness for mixtures of trifluoroiodomethane (CF3I) with carbon dioxide (CO2) under development as a drop-in halon replacement for onboard aircraft fire suppression systems. Through both experimental measurements and flame simulations using detailed chemical kinetics, we demonstrated that the extinguishment performance of CF3I-CO2 blends can be superior to that of the individual components alone. The extinction concentrations were determined for different CF3I-to-CO2 ratios introduced into ambient air using a heptane cup burner. The extinction concentrations for pure CF3I in air (3.36 ± 0.13% vol.) and CO2 in air (20.74 ± 0.64% vol.) are in close agreement with previously reported values, and first-time extinction concentration data for CF3I-CO2 blends are reported. To elucidate important reaction pathways, detailed chemical mechanisms have been compiled for modeling methane-, propane- and heptane-air flame inhibition at ambient conditions. These mechanisms were constructed from published sub-mechanisms for C7 and C1-C3 hydrocarbons and hydrofluorocarbons with additional oxidation chemistry developed for trifluoroiodomethane. The latter sub-mechanism contains 14 species and 91 reactions. Using the CANTERA software package, critical concentration values of CF3I-CO2 mixtures in air for extinguishing methane, propane, and n-heptane counterflow flames were determined and compared against experimental non-premixed flame extinction data.

A Review on Geothermal Renewable Energy Systems for Eco-Friendly Air-Conditioning

Nowadays, air conditioning consumes, on average, around one-fifth of the total power used in buildings globally. The present paper aims to provide the present status on the employment of Earth-to-Air Heat eXchangers (EAHX) to contain the consumption of energy and to reduce the effect on the environment in response to the Montreal and Kyoto protocols in a way to achieve cleaner energy production with a low Global Warming Potential (GWP) and a low ozone depletion potential (ODP). Different peculiarities and applications (direct or hybrid) are critically analyzed and reviewed. Specifically, in this paper, the different hybrid applications presented in the literature, where the Earth-to-Air Heat eXchangers are coupled to advanced systems, are reviewed. Finally, an IoT-based EAHX control system plan is reported and discussed to optimize energy efficiency and thermal comfort to suit operating conditions under different time zones.

Thermodynamic Optimization of Low-Temperature Cycles for the Power Industry

The fuel price increase and severe environmental regulations determine energy-saving importance. Useful utilization of low-potential heat sources with 300–400 °С temperature becomes topical. The application of low-temperature power production facilities operating low-boiling heat carriers could be a solution to this problem. A comparative parametric study of a number of heat carriers resulted in a choice of the most promising fluids that are not expensive, have low toxicity and flammability, low ozone depletion and low global warming potential. These heat carriers are considered for application in simple power production cycles with and without regeneration. The main parameters were optimized at the initial temperatures of 323.15–623.15 K. The cycle without regeneration has a maximal net efficiency of 29.34% using the water at an initial temperature of 623.15 K. The regenerative cycle at a temperature below 490 K has its maximal efficiency using a water heat carrier, and at a higher temperature above 490 K with R236ea. The cycle with R236ea at 623.15 K has an electrical net efficiency of 33.30%. Using a water heat carrier, the maximal efficiency can be reached at pressures below 5 MPa for both cycles. Among the organic heat carriers, the minimal optimal initial pressure of a simple cycle is reached with the R236ea heat carrier below 45 MPa without regeneration and below 15 MPa with regeneration. Therefore when utilizing the latent heat with temperatures above 500 K R134a, R236ea and R124 are the most promising organic fluids. Such conditions could be obtained using different industrial sources with water condensation at elevated pressures.

Performance analysis of HCFCs, HFCs and natural refrigerants under different working conditions based on single-stage vapor compression system

Environmental problems such as the destruction of the ozone layer and global warming force people to choose refrigerants. It has become an inevitable trend to look for refrigerants with low ODP (Ozone Depletion Potential) and GWP (Global Warming Potential) to replace the refrigerants that are harmful to the environment. In addition, we also need to consider the COP (Coefficient Of Performance) and safety of refrigerants. This paper is based on a single-stage vapor compression refrigeration system, The COP of different refrigerants are calculated and analyzed under five different working conditions. After calculation, the COP of R717 is the highest under five working conditions, and its GWP is 0, but its safety level is only B2L.Therefore, it is very difficult to take into account the various properties of refrigerants at the same time.

Solubility behavior of 3, 3, 3-trifluoropropene in 1-hexyl-3-methyl-Imidazolium hexafluorophosphate and 1-octyl-3-methyl-imidazolium hexafluorophosphate

Due to low global warming potential and ozone depletion potential, 3, 3, 3-trifluoropropene (HFO1243zf or R1243zf) has attracted much attention. 1-Hexyl-3-methyl-imidazolium hexafluorophosphate ([HMIM][PF6]) and 1-octyl-3-methyl-imidazolium hexafluorophosphate ([OMIM][PF6]) with strong absorbability and hydrophobicity are assumed as potential absorbents in absorption refrigeration cycle. In this work, the solubility of R1243zf in [HMIM][PF6] and [OMIM][PF6] was measured based on isochoric saturation method under seven temperatures (283.15 K, 293.15 K, 303.15 K, 313.15 K, 323.15 K, 333.15 K and 343.15 K). The experimental solubility data was correlated using the non-random two liquid (NRTL) and Krichevsky-Kasarnovsky (K-K) model, and both models showed reasonable results. In addition, the Henry’s law constants and mixing thermodynamic properties (mixing enthalpy, entropy and Gibbs energy) for R1243zf + [HMIM][PF6] and R1243zf + [OMIM][PF6] solutions were computed, and their variation with solubility was analyzed. Besides, the dissolving performances of different HFOs (R1234ze(E), R1243zf and R1234yf) in [HMIM][PF6] and [OMIM][PF6] were compared and analyzed on basis of the published data in the literature.

Exergy analysis of heat assisted ejector refrigeration system using R1234yf

An ejector refrigeration system (ERS) is introduced which operates on low-grade energy like solar energy, industrial waste heat etc. In this paper, the performance parameters and the conventional exergy analysis of ejector refrigeration system is measure with reference to ambient conditions. Exergy analysis was applied independently to each component of the system. The refrigerant R1234yf which has low Ozone depletion potential (ODP) and Global depletion potential (GWP) has been used to analysed the exergy analysis with the help of Engineering Equation solver software. The results shows that maximum exergy destruction in generator followed by ejector and other components.

Suppression of disproportionation reaction of HFO-1123 using inhibitors

Abstract Trifluoroethene (HFO-1123) has a very low global warming potential (GWP) and ozone depletion potential (ODP); thus, it has been proposed as a next-generation refrigerant. However, a short circuit in a motor under high temperature and pressure conditions may cause a disproportionation reaction of HFO-1123. Therefore, to commercialize a split air conditioner using HFO-1123, it is necessary to develop a technology to suppress this disproportionation reaction. In this study, disproportionation experiments were conducted under various temperature and pressure conditions. Variations in pressure, temperature, and input energy were recorded. Using a discharge method, we experimentally determined the threshold pressure of the disproportionation reaction. The disproportionation reaction was photographed using two high-speed cameras, and the flame temperature was measured using the two-color temperature radiometry method. The experiment was conducted using R32 and trifluoroiodomethane (R13I1) as the disproportionation reaction inhibitors, and the suppression effect of the disproportionation reaction was evaluated.

The Status of Thermodynamic Data and Models for CF3I and its Mixtures ⋆.

There is a renewed interest in the use of the refrigerant CF3I for refrigeration and air-conditioning applications, driven by its low global warming potential (similar to that of CO2), low (but nonzero) ozone depletion potential, and its ability to suppress flammability. In this paper the existing thermodynamic data for this fluid are summarized. Furthermore, as CF3I has been proposed as a component in mixtures with other refrigerants, the emphasis of this paper is on the survey of existing mixture data and an assessment of the suitability of existing thermodynamic modeling approaches and estimation schemes to model the properties of these mixtures. For mixtures where sufficient data exist, interaction parameters have been optimized.

The potential of halogenated olefins as working fluids for organic Rankine cycle technology

The phase-out of hydrofluorocarbons triggered by the enforcement of new environmental regulations forces the search for new substances that comply with the stricter environmental requirements, while offering similar thermodynamic performance and safety features. Olefins containing fluorine and/or chlorine have the potential to be used as replacement fluids with sufficient performance. Currently, only a few halogenated olefins are available on the market for their use as refrigerants or working fluids, but the potential of all other possible olefinic molecules has not yet been studied. In this work we present a comprehensive evaluation of halogenated olefins of up to five carbon atoms, containing fluorine and/or chlorine, as potential working fluids for use in organic Rankine cycle power systems. To this end, tailored predictive models for the thermophysical properties of the considered olefins are used to explore the potential use of halogenated olefins having low global warming potential and low ozone depletion potential as working fluids for organic Rankine cycle power systems. The results indicate that options with good thermodynamic performance exist for both low and high temperature applications, each of them implying the use of more fluorinated or more chlorinated olefins, respectively. Preliminary estimates indicate reasonable environmental and safety features for these options, however, a deeper study to confirm their compliance with regulations on ozone protection or global warming should be carried out for their future use. Furthermore, these options may be considered as future replacements for current flammable working fluids for high temperature applications, where they may even outperform them in terms of net power output.

Review of Heat and Mass Transfer Enhancement Techniques and Current Advancement for Adsorption Heating/Cooling Systems

Abstract Adsorption heating/cooling became an alternative to vapour compression system due to low ozone depletion potential (ODP) and global warming potential (GWP). However, more investigation is required due their low efficiency when compared to conventional heating/cooling systems. This review emphasizes on the mathematical modelling simplification and heat transfer enhancement method that applied by many researchers to improve the performance of adsorption heating and cooling technologies. Various techniques investigated by many researchers on solving low thermal conductivity and the different methods for enhancing heat and mass transfer in the adsorbed bed/pipe also discussed. Common techniques used to enhance heat and mass transfer in the adsorbed bed/pipe include the fin type adsorbent tube/ heat exchanger, amalgamated adsorbent bed with a metal foam, consolidated adsorbent, adsorbent coating and adsorbent with multi cooling tubes. Other than that, recent advancements in adsorption cooling/heating systems also discussed in this review.

Study and Analysis of Capillary Tube and Thermostatic Expansion valve in Domestic Refrigerator using Eco friendly Refrigerant : A Review

The current review is concerned with the study of the effect of different expansion devices (capillary tube and Thermostatic expansion valve) on the alternative refrigerants used in the domestic refrigerators to have better performance with minimum losses. This paper give the summary and range of various refrigerants used in the refrigeration cycle of global warming which affect the environment by the use of refrigerant, and our aim is to reduce the effect of global warming as well as optimize the performance of domestic refrigerators by using the latest refrigerants and appropriate expansion devices like capillary tube and Thermostatic expansion valve. R134a is used in vapor compression refrigeration system having zero ozone depletion potential (ODP) and almost good thermodynamic properties, but it has a high Global Warming Potential (GWP) of 1300.So many researchers identifying new refrigerants and their blend which are environmental friendly and having low GWP and low ODP. Hydrocarbon refrigerants mainly propane, butane and isobutene are proposed as an environment friendly refrigerants. After reviewing the various literatures on the various expansion devices and hydrocarbons refrigerants and their mixture gives good performance in small capacity domestic refrigerator.

Investigation on Thermo-Physical Properties of Mixed Nano-Refrigerant with CuO based nanoparticles

Over the past few decades, development of nanotechnology has been made its mark in the various fields of research. Further, the energy consumption has seen an increment with the increasing refrigeration and air conditioning systems in numbers. However, to overcome the energy crisis globally the need of highly efficient systems becomes a necessity. At the same time, preventing the environment by these technological leaps becomes challenging. In view of environmental impacts of these technologies Montreal Protocol Treaty was signed in 1987 to restrict the use of substances such as chlorofluorocarbons damaging the ozone layer and was enforced from January 1989. Whereas, Kyoto Protocol Treaty signed in 1997 to restrict usage of high valued Global Warming Potential substances such as hydrofluorocarbons and was enforced on February 2005 onwards. Therefore, using low ozone depletion potential and low global warming valued refrigerants such as R-600a, R-290, etc. becomes an effective substitute. In this study, the thermophysical properties of mixed nano-refrigerants made from mixing R-290 and R-600a with nanoparticles has been estimated using fluid data available in NIST database standard 4 (SUPERTRAP®) versions 3.2.1. Further, the effect of volume concentration of nanoparticles in mixed refrigerant (R-290 and R-600a) on density, thermal conductivity, viscosity and specific heat is investigated. In addition, the effect of pressure on these properties is also investigated

Experimental investigations into power generation with low grade waste heat and R245fa Organic Rankine Cycles (ORCs)

In this study, experimental research was conducted to investigate the performance of a small-scale Organic Rankine Cycle (ORC) system utilising low grade heat sources to generate electric power at different operating conditions. The experiment setup consisted of typical ORC system components, such as a turboexpander with high speed generator, finned-tube condenser, ORC pump and plate evaporator. R245fa was selected as a working fluid in the experimental system, considering its appropriate thermosphysical properties for the ORC system and low ozone depletion potential (ODP). At constant heat sink (ambient) parameters, extensive experiments were carried out to examine the effects of various important parameters including heat source temperature and working fluid pump speed etc. on system performance. Results showed that at a fixed working fluid speed, the thermal efficiency of the tested ORC system could be improved with an increased heat source temperature. On the other hand, at a constant heat source temperature, the working fluid pump speed could be optimised to maximise system thermal efficiency. Both the heat source temperature and ORC pump speed were found to be important parameters in determining system thermal efficiency and the component operations. The experimental outcomes can instruct future optimal system design and controls.

Feasibility of drying system using waste heat as the heating source

In this study, a wastewater heat pump system was proposed and its thermal performance was analyzed. The proposed system includes two evaporators: an air-source evaporator and a water-source evaporator. The air-source evaporator absorbs heat from the moist hot air which exhaust from the drying oven. The water-source evaporator absorbs heat from the waste water, while the waste water recovers heat from the mechanical energy, which was produced by cutting and polishing in stone production. The thermodynamic model was developed to evaluate the performance of the proposed system. The energetic analysis was carried out to investigate the influences of the temperature of fresh air. The results show significantly higher energy efficiency, compact-sized and energy-saving compared with the system which uses air as the heat source. Among the seven of alternative refrigerants (R152a, R123, R1234yf, R1234ze, R600a, R22 and R600) investigated, R123 was suggested to be used in this heat pump for its high heating efficiency, inflammable, very low ODP(Ozone Depletion Potential) and GWP(Global warming potential).