Refrigeration and Air conditioning

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Computer-Aided Thermofluid Analyses using Excel Mohamed Musadag El-Awad

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The negative influence of refrigerants on the climate and the immediate environment in terms of their higher global warming potential (GWP) and ozone depletion potential (ODP) has prompted this study. Currently, natural refrigerants are the preferred alternative refrigerants and hydrocarbon is numbered among these natural refrigerants with zero ODP and negligible GWP. In order to improve and enhance the performance of the refrigeration system, the performance characteristics of the system were investigated experimentally using eco-friendly refrigerant HC600a as alternative to HFC134a. In addition, comparisons were made using refrigerant mass charge of 46 g of isobutane (HC600a) and 70 g of conventional refrigerant (HFC134a). Thermodynamic parametric analysis was conducted using electric power consumption, coefficient of performance (COP), cooling load and pull-down time (PDT) for the used mass charges. REFPROP software was applied to capture the thermodynamic properties of the vapou...

In this study, the effects of sub-cooling on the various refrigeration cycle performance parameters using the alternative refrigerants (R432A and R433A) as working fluids were evaluated theoretically and compared with those obtained using the baseline refrigerant (R22). The results obtained showed that the thermodynamic properties of R432A and R433A matched those of R22 and they could be used as substitute for R22. The two alternative refrigerants exhibited very high thermal conductivity with average values of 59.3% and 58.0% higher than that of R22, respectively. Their condenser duties are also better than that of R22, which shows that they could perform very well as refrigerants in heat pump systems. They exhibited higher coefficient of performance (COP) and higher relative capacity index (RCI) than R22. The average COPs obtained for R432A and R433A were 12.9 and 16.7% higher than that of R22. They also exhibited lower power per ton of refrigeration (PPTR) than that of R22, but R433A emerged as the most energy efficient refrigerant among all the investigated refrigerants with average reduction in PPTR of 28.5% higher than that of R22. Generally, incorporation of sub-cooling heat exchanger in the system, greatly improved the performance of the system; it increased the COP, reduced the compressor energy input and the specific power consumption of the system. The two alternative refrigerants, consistently exhibited better performance than R22 in sub-cooling heat exchanger refrigeration system. R433A performed better than both R22 and R432A in that the highest RCI, COP, reduction in energy input, reduction in PPTR and lowest discharge temperature were obtained using R433A in the system.

Now days, global warming is one of the serious concern for environment to get protected from it every one is taking help of technology by the means of different types of refrigeration system for comfort food process, medicines, blood storage, humidity control, etc. use of refrigeration system not totally green or ineffective environment, if we can use proper eco-friendly refrigerant in refrigeration system and make number of refrigeration system less. Then it is not long way to be resolve global warming issue. In India middle class and poor families cannot afford all types of Refrigeration system like as AC, Refrigerator, Air cooler, etc. Generally they purchase only Air cooler. To solve this we can integrate Refrigeration system of AC, refrigerator and Air cooler in one product. So, that it cans multiplication and can we say as multifunctional Refrigeration system. This type’s product various components are used like as compressor, condenser, capillary tube, evaporator, motor, fan, etc

This paper presents a theoretical investigation of the performance of R432A and R433A refrigerants as alternatives to ozone depleting R22 refrigerant. The two refrigerants have zero ozone depleting potential and negligible global warming potential. The results obtained showed that the properties of the three investigated refrigerants are similar. The saturation vapour pressures for R432A and R433A, between saturation temperatures of -30 to 40oC, are 99.6 and 99.3% the same with that of R22. The performance of R22 in terms of power per ton of refrigeration (PPTR), Volumetric Refrigeration Capacity (VRC) and Coefficient of Performance (COP) is slightly better than those of the two alternative refrigerants. The average COPs obtained for R432A and R433A were slightly lower by 4.5 and 5.4% than those of R22, respectively, but the two alternative refrigerants equally exhibited better pressure ratio, discharge temperature and pressure than R22. Both R432A and R433A have higher refrigeratin...

In present situation, reduction of energy consumption is necessary due to continuous increase in energy demand and reduction in global energy supply. Coefficient of performance of air conditioning system can be increased with evaporative cooled condenser in place of air cooled condenser. This paper presents a broad review of evaporative cooled condenser used in residential and commercial cooling systems. Evaporative cooled condenser increases the heat rejection process with the cooling effect of evaporation and therefore improve coefficient of performance. It is found by using evaporative cooling condenser, the power consumption can be decreased upto 20 % and coefficient of performance can be increased around 50%.

Energy conservation is a buzzword that cuts across a broad spectrum of stakeholders. It has been widely practiced, developed, and discussed in government, political, and industrial sectors due to its massive impact on tackling issues related to climate change and global warming as well as presenting opportunities to cut energy costs. Despite the active discussion of this topic in the literature, very few papers have discussed it in the context of academic institutions which has one of the most significant impacts in terms of energy consumption. To address the issue, this paper places the topic of energy conservation in the context of academic institutions. Moreover, it adopts the Theory of Planned Behavior to investigate the success of energy conservation initiatives in academic institutions by looking at user behavior and its antecedents. Finally, this paper contributes significantly to the literature as it is one of the very few papers and arguably the first to discuss energy conservation in the context of academic institutions using the Theory of Planned Behavior. Furthermore, this paper will be beneficial for practitioners and other stakeholders in that it provides them with a framework to investigate the success of implementing energy conservation initiatives, especially, in academic institutions by looking at the antecedents of user behavior.

The paper presents a theoretical investigation into the performance of R432A and R433A refrigerants as alternatives to the ozone depleting R22 refrigerant. The two refrigerants have zero ozone depleting potential and a negligible global warming potential. The results obtained showed that the properties of the three investigated refrigerants are similar. The saturation vapour pressures for R432A and R433A, between the saturation temperatures of -30 to 40C, are 99.6 and 99.3% the same as that of R22. The performance of R22 in terms of power per ton of refrigeration (PPTR), volumetric refrigeration capacity (VRC) and coefficient of performance (COP) is slightly better than the performance of the two alternative refrigerants. The average COPs obtained for R432A and R433A were lower by only 4.5 and 5.4%, respectively, than those of R22, but the two alternative refrigerants equally exhibited better pressure ratios, discharge temperatures and pressures than R22. Both R432A and R433A have h...

This paper presents a theoretical investigation of the performance of R432A and R433A refrigerants as alternatives to ozone depleting R22 refrigerant. The two refrigerants have zero ozone depleting potential and negligible global warming potential. The results obtained showed that the properties of the three investigated refrigerants are similar. The saturation vapour pressures for R432A and R433A, between saturation temperatures of -30 to 40oC, are 99.6 and 99.3% the same with that of R22. The performance of R22 in terms of power per ton of refrigeration (PPTR), Volumetric Refrigeration Capacity (VRC) and Coefficient of Performance (COP) is slightly better than those of the two alternative refrigerants. The average COPs obtained for R432A and R433A were slightly lower by 4.5 and 5.4% than those of R22, respectively, but the two alternative refrigerants equally exhibited better pressure ratio, discharge temperature and pressure than R22. Both R432A and R433A have higher refrigeratin...

This paper study the performance evaluation of a refrigeration system that operates on solar energy as alternative source of power to enhance the refrigerating effect, coefficient of performance (COP), preservation of perishable items and short time drug such as vaccine, to remote communities and parts of the urban settlement around the developing nations where there is no access to modern electrical source. The system was made from locally sourced materials using a conventional refrigerant HFC134a as working fluid to improve thermal efficiency and stability of the vapour compression refrigeration system. The COP of the system was enhanced by 8.67% when working with solar and with energy reduction of 2.38% respectively. In case the weather is cloudy or during the night hour when the energy generation is low, the refrigerator can work on battery for an average of 12 hours if fully charge during the day to avoid idle time of the refrigeration system.

Nano refrigerant is nothing but the combination of nano-particle with the refrigerant for the sake of better refrigeration process. It has been observed that, as compared to alternative refrigerant, there is better improvement in heat transfer capacity of the refrigerant after addition of nanoparticles. The use of nano-particles along with the conventional refrigerant with vapour compression cycle is relatively a new idea, where nano-refrigerants, so obtained are found to have their improved thermo-physical properties over the conventional refrigerants. Nano-particles can be used along with refrigerant in order to improve the performance of vapour compression refrigeration system. In this paper, alumina (Al2O3) nanoparticles of 50 nm diameter are dispersed in refrigerant R134a to improve its heat transfer performance to have their improved thermal & physical properties over the conventional refrigerants.

Encompassing both practical applications and recent research developments, this book takes the reader from fundamental physics, through cutting-edge new designs of ejectors for refrigeration. The authors’ unique vision marries successful design, system optimization, and operation experience with insights on the application of cutting-edge Computational Fluid Dynamics (CFD) models. This robust treatment leads the way forward in developing improved ejector technologies. The book covers ejectors used for heat powered refrigeration and for expansion work recovery in compression refrigerators, with special emphasis on two-phase flows of “natural” fluids within the ejector, i.e. steam and carbon dioxide. It features worked examples, detailed research results, and analysis tools.

The adsorption refrigeration system is an alternative refrigeration system powered by thermal source so that it is possible to use waste heat and solar energy. This paper reports the experiment of the ethanol-activated carbon (AC) as the adsorbateadsorbent pair. Experimental work was conducted with two adsorption beds as thermal compressor. Ethanol-AC pair can be operated with the heat source temperatures 90oC and 100oC for different heat sink temperature 20oC, 25oC and 30oC, respectively. The experimental result shows when temperature of the hot water 100oC and the cooling water temperature 30oC, the system give the higher coefficient of performance (COP) than another testing operation condition. Additionally, the COP of the system is varying a long operating in average 0.19 due to manually intermittent operation of both adsorption beds. The maximum adsorption capacity is 0.302 kg/kg·AC while the desorption temperature, desorption pressure and heating time of the adsorption bed are...

Encompassing both practical applications and recent research developments, this book takes the reader from fundamental physics, through cutting-edge new designs of ejectors for refrigeration. The authors’ unique vision marries successful design, system optimization, and operation experience with insights on the application of cutting-edge Computational Fluid Dynamics (CFD) models. This robust treatment leads the way forward in developing improved ejector technologies. The book covers ejectors used for heat powered refrigeration and for expansion work recovery in compression refrigerators, with special emphasis on two-phase flows of “natural” fluids within the ejector, i.e. steam and carbon dioxide. It features worked examples, detailed research results, and analysis tools.

The present paper describes a novel CFD approach for the flashing of CO2 through nozzles and ejectors. The novelty of the method is represented by the possibility of defining both the liquid and vapor phases as compressible materials. The properties of each phase are obtained via look-up tables calibrated against standard fluid libraries and are valid in the whole domain of interest, including the supercritical, subcritical and metastable regions. The model has been implemented within a commercial CFD solver and is completely general, i.e., it can be applied to any type of compressible multiphase flow. In the present study, the proposed approach has been validated against an experimental test-case available in literature.

In this paper, the advanced exergy analysis was applied to a R744 booster refrigeration system with parallel compression taking into account the design external temperatures of 25 °C and 35 °C, as well as the operating conditions of a conventional European supermarket. The global efficiencies of all the chosen compressors were extrapolated from some manufactures' data and appropriated optimization procedures of the performance of the investigated solution were implemented. According to the results associated with the conventional exergy evaluation, the gas cooler/condenser, the high stage (HS) compressor and the medium temperature (MT) display cabinet exhibited the highest enhancement potential. The further splitting of their corresponding exergy destruction rates into their different parts and the following assessment of the interactions among the components allowed figuring out the real achievable improvements. The avoidable irreversibilities of the HS compressor and that of the MT evaporator were mainly and completely endogenous, respectively. On the other hand, the gas cooler/condenser could be predominantly improved by decreasing the inefficiencies of the MT evaporator. As regards the auxiliary compressor, large enhancements were attainable through the drop in the irreversibilities occurring in the remaining components.

This paper study the performance evaluation of a refrigeration system that operates on solar energy as alternative source of power to enhance the refrigerating effect, coefficient of performance (COP), preservation of perishable items and short time drug such as vaccine, to remote communities and parts of the urban settlement around the developing nations where there is no access to modern electrical source. The system was made from locally sourced materials using a conventional refrigerant HFC134a as working fluid to improve thermal efficiency and stability of the vapour compression refrigeration system. The COP of the system was enhanced by 8.67% when working with solar and with energy reduction of 2.38% respectively. In case the weather is cloudy or during the night hour when the energy generation is low, the refrigerator can work on battery for an average of 12 hours if fully charge during the day to avoid idle time of the refrigeration system.

This paper presents a theoretical investigation of the performance of R432A and R433A refrigerants as alternatives to ozone depleting R22 refrigerant. The two refrigerants have zero ozone depleting potential and negligible global warming potential. The results obtained showed that the properties of the three investigated refrigerants are similar. The saturation vapour pressures for R432A and R433A, between saturation temperatures of -30 to 40oC, are 99.6 and 99.3% the same with that of R22. The performance of R22 in terms of power per ton of refrigeration (PPTR), Volumetric Refrigeration Capacity (VRC) and Coefficient of Performance (COP) is slightly better than those of the two alternative refrigerants. The average COPs obtained for R432A and R433A were slightly lower by 4.5 and 5.4% than those of R22, respectively, but the two alternative refrigerants equally exhibited better pressure ratio, discharge temperature and pressure than R22. Both R432A and R433A have higher refrigeratin...

ABSTRACT This paper presents the design, construction and performance testing of a refrigeration system for use as experimental apparatus for demonstrating vapour compression refrigeration cycle and basic concepts of thermodynamic principles. The apparatus shows the visual observation of all-important processes. The experimental data were analysed using the first and second laws of thermodynamics to determine the refrigerating effect, the net heat rejected from the system, the compressor work input and coefficient of performance (COP). During the test, the COPs of the system and Carnot cycle were found to be 3.87 and 6.96, respectively. Also, the steady state discharge pressure and the average refrigeration capacity obtained were 830 kPa and 915.8 W, respectively, while the relative and isentropic efficiencies obtained from the system were 55.6 and 86.7%, respectively.

Indesigning air conditioning system, global warming effect within a region isa very important factorbecause itcanaffect theperformanceor the efficiency and the electricityconsumptionof theair conditioning system. The increase in outsideor environment willincrease theheat loadthatmust becontrolled by the air conditioning system. This studyis aimedtoanalyze theincrease of outsideairtemperatureor the environment inthe City ofBandung, West Java, Indonesia on theperformance ofthe air conditioning system andelectricenergyconsumption. Resultsof this studyindicatethatan increase inoutsideor environment air temperaturebyr1oFreducethe cooling power (refrigerating effect) by0.5Btu/ lb, in average and increases thetheoreticalcompressorpower by 0.39Btu/lb in average. The increase in outside air temperature by 1oF also decreases the Coefficient ofPerformance (CoP)in averageby 0.3; decrease the refrigerantcirculationinthe systemin average by 0.025lb/ton-min, andraises electricenergyconsumptionin a...

A thermodynamic study of single- and double- effect vapour absorption systems working with the fluid pair Trifluoroethanol and N-methyl Pyrrolidone is presented, keeping in view the applications of the systems for refrigeration, air-conditioning and heat pumping. Results are presented in the form of graphs for the variation of the coefficient of performance, circulation ratio and exergetic efficiency. The performances of single- and double-effect systems working with the pairs Trifluoroethanol - N-methyl Pyrrolidone and water-lithium bromide are compared. For both single and double-effect systems, the water-lithium bromide pair has higher Coefficient of Performance and lower start-up temperature. Despite these facts, Trifluoroethanol - N-methyl Pyrrolidone can be a potential alternative to water-lithium bromide in view of the disadvantages of water-lithium bromide pair such as recrystallization, corrosion and freezing of the refrigerant at sub-zero temperatures.

The paper presents a fine bubble generator with orifice achieved based on micro-drilling technologies. The equation that determines the variation speed of dissolved oxygen concentration in the water is integrated using implicit Runge-Kutta method. The study presents the theoretical and experimental results conducted on a laboratory installation equipped with modern measurement devices.