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In a vapor compression refrigeration and air conditioning system, two-phase flow of refrigerant generally takes place in the condenser and evaporator. Different flow patterns can be found the condenser pipe depending on the position of the pipe relative to the inlet and outlet side. Investigation on the behavior of refrigerant void fraction in a horizontal condenser of a 5.28 kW air conditioner using R290 has been carried out. The void fraction was calculated by using data of refrigerant enthalpy, vapor quality, density, and volume of refrigerant in a pipe segment. In general, refrigerant mass vapor quality of refrigerant is almost identical for different condensing temperature. At the position near the pipe inlet, the void fraction is maximum and drops at a slower rate until it reaches 0.7 of length of the pipe. From this position to the outlet of condenser, the void fraction decreases at a higher rate. The variation of refrigerant density along the condenser pipe causes the lower rate of change of void fraction at the position near the inlet and higher rate of change of void fraction near the condenser outlet. [ABSTRACT FROM AUTHOR]

One of the oldest techniques used by men to cool their homes was evaporative cooling. It has only recently been placed on a stable thermodynamic foundation. Different from conventional air conditioning systems that employ vapor-compression or absorption refrigeration cycles is evaporative cooling. Evaporative cooling offers comfort by filtering and circulating the cooled air; it does not perform all the duties of genuine air conditioning. In this paper we tried to synchronize the discharge water with fan speed, using the fine coconut coir as a cooling pad material, design and fabrication of the air cooler in order to dismantle it into parts for easy carrying and maintenance purposes. The efficiency of the fabricated air cooler has been improved compared with the existing air cooler. The detailed mechanism and working principle of the air cooler has been discussed in the following sections. [ABSTRACT FROM AUTHOR]

Indirect evaporative cooling is an efficient, sustainable, low-energy alternative for many refrigeration applications in dry climates. However, the indirect evaporative cooling performance deteriorates severely at high air humidity. To overcome these limitations, it investigates the process that binds the indirect evaporative cooling and vapor compression cycles together to overcome these limitations. Therefore, a new hybrid cooling system was designed and built that combines them because the hybrid system completely used outside fresh air. This hybrid process takes advantage of the high efficiency for indirect evaporative cooling and the vapor compression cycle capacity to control the temperature and humidity of the conditioned air while improving the total annual energy consumption. A theoretical study was conducted using the heat exchanger's fundamental principles of energy balancing. A created computer program was in (Fortran's 90) language to study the system performance and the system's appropriate environmental and design conditions. An experimental study was also conducted to test the hybrid system under different climatic conditions and then compare it with the theoretical study. The experimental study of the system was conducted at (the University of Tikrit). Which is located on the (34. 67N; 43.65 E), to determine the suitability of the weather conditions in the region for the operation of this system. The experiment was conducted at the beginning of (Jun/2022) for two consecutive days during (24) hours of reading. The experimental results showed that the best performance of the hybrid system was achieved when the amount of air supplied was (0.64 m3/s) for the dry channel and (0.54 m3/s) for the humid channel, as the length of the exchanger tube. (35 cm) and tube diameter (1.5 cm) show that the supplied air temperature decreases significantly. The outside fresh air temperature supplied to the air-conditioning space can be lowered by (20-26°C). The coefficient of performance for indirect evaporative cooling is in the range of (27.8-55.2) compared to the vapor pressure cycle in the range of (3.7-5.6), and the overall coefficient of performance of the hybrid system will be (15.8-23.7) so the reduction in electricity consumption in the range (25-50%). [ABSTRACT FROM AUTHOR]

The research paper presents an experimental investigation into the functioning of an absorption refrigerator, executed at the University of Technology and Applied Sciences-Al Musannah in Oman. The study focused on comparing the effects of two types of input energies, solar-thermal and solar-electrical, on the system's functionality. This was done in an effort to identify a more environmentally friendly alternative to traditional cooling systems, such as vapor compression refrigeration systems (VCRS), which contribute to environmental problems through greenhouse gas emissions. Using a data acquisition system, key parameters including temperatures at specific points, solar intensity, fluid flow rates, and electric power output were collected and analyzed. The effectiveness of the system, as measured by the coefficient of performance (COP) of the system, under diverse operating settings was assessed. The findings were subsequently interpreted and illustrated. One key discovery was that the system's COP was approximately 13% higher when powered by solar-electric energy than solar-thermal energy. Furthermore, using solar-electric energy resulted in a nearly 14% increase in the refrigeration effect compared to solar-thermal energy, indicating the potential of solar-powered vapor absorption refrigeration systems as an eco-friendly option. [ABSTRACT FROM AUTHOR]

The development of thermoacoustic refrigerators has been hindered by their low coefficients of performance and cooling load. This paper reports on literature on studies that sought to optimise individual and entire thermoacoustic refrigerator performance. These studies investigated individual components and suggested that a pin array stack with smaller spacing should be preferred. According to previous studies, developers of thermoacoustic refrigerators should select low thermal conductivity materials such as Mylar sheet, PLA or RVC. They should use low Prandtl number fluids, such as the Helium-Xenon mixture. The stacks should be short and positioned nearer the closed end of the resonator. Also, they should operate the thermoacoustic refrigerators at higher than atmospheric pressures for better performance. These optimal parameters sometimes work in a contrary manner, therefore is necessary to optimise the thermoacoustic refrigerator's geo-metric and operating parameters. Numerical studies which show that when properly optimised, thermoacoustic refrigerators can achieve coefficients of performance comparable to vapour compression systems are yet to be validated by experiment. [ABSTRACT FROM AUTHOR]

Most household refrigerators employ vapor compression refrigeration technology, which has a high coefficient of performance. The system is constructed using components such as the compressor, condenser, expansion valve, and evaporator. The performance of the system is determined by each component, and each component has the capacity to ultimately increase or decrease system performance. Using a modified condenser arrangement, the research report describes how to increase the COP of a residential refrigerator. The use of a micro channel condenser boosts the coefficient of performance (COP) of a refrigerator; the shape and increased surface area of such micro channels have been proven to have positive impacts on the COP value, as described in a research paper. Comparing the outcomes of installing a micro channel condenser to those of a conventional refrigerator reveals that they are worthy of appreciation. Installing a micro channel type condenser improved the COP by 2.20 and 2.63 percent, respectively. The baseline for comparison is the COP of a household refrigerator with a traditional condenser system. [ABSTRACT FROM AUTHOR]

A mathematical model for the determination of energy and exergy of system is presented. It is used to investigate the results and find out the relation between evaporator temperature, evaporator pressure, condenser temperature and condenser pressure on the exergy loss, second law efficiency and coefficient of performance. It is found that the exergy loss in evaporator is very much dependent on evaporator temperature and pressure, the same situation is found in condenser also. It is also found that refrigerant R1234yf has the minimum total exergy loss and highest second law efficiency. According to results obtained it can be concluded that selected refrigerants can be a good substitute to R134a. [ABSTRACT FROM AUTHOR]

The artery of the induction coil (IC) in coreless induction furnaces is the water-cooling system. The IC conductor is a hollow tube of high electrical and thermal conductivity copper. This coil must be water-cooled to maintain its temperature at less than 75℃ during the heating process. The goal of this work is applying a proposed approach to reach the minimum required velocity of the coolant inside the IC tube, able to perform the required limit. The IC under study is designed to melt 25 kg of a scrap copper charge in a carbon crucible. Two sources of heat affect the IC, the crucible enclosing the melt and that due to the high current of high frequency passing through it. Then, this research is intended to avoid the rise of IC temperature and its damage during the process, by considering the electromagnetic-thermal analysis to determine the surrounding temperature at the charge's melting point without cooling, then the obtained data is used as an input to the thermal-fluid analysis step to calculate the required cooling time and the required velocity of the coolant. The calculations based on the difference in temperature between the outlet hot water and the inlet cold water. The mass flow rate and the required water velocity through the induction coil are mostly computed by both, the traditional analytical method and by numerical method. A comparison between them is discussed and suggestions of the required cooling arrangements are mentioned. Since, the cooling time is less than that of the melting process, then the cooling system can be adopted. The finite element method (FEM) is considered in this study by using the ANSYS computer package to model and simulate such a problem. [ABSTRACT FROM AUTHOR]

This paper studied the impact of using CuO nano-particles of 50nm size in a Vapor Compression Refrigeration System (VCRS), along with Poly-alkylene Glycol (PAG) oil, and R-134a mixed to form a nano refrigerant. In this work, the nanoparticles were performed in three different volume fractions (0.1%, 0.3%, and 0.5%) and mixed with 200ml of the PAG oil. A VCR system was built at the mechanical engineering department laboratory in al-qadisiyah University to study the Coefficient of Performance (COP) and the system's energy consumption with and without the addition of the nanoparticles. The paper resulted in a raise in systems COP by 41.7% when using concentration of 0.5% of CuO/PAG oil/R-134a and a reduction in the power consumption by 24.32% compared to when using a pure R-134a/PAG oil. Also, the nano refrigerant appeared to be safe, harmless, and more efficient for use in vapor compression systems. [ABSTRACT FROM AUTHOR]

Vapor compression refrigeration system (VCRS) is the most commonly used refrigeration system in refrigeration and air conditioning industry. It is the most efficient and responsive system in field of HVAC. VCRS mainly works on principle of evaporation i.e., when liquid evaporates it absorbs latent heat from surroundings and cooling effect is produced. In this work, new blends of several working substances i.e refrigerants are made. These blends are made according to their thermodynamic properties and several other parameters are also considered. These new blends are made according to several ratios by mass like (50/50), (60/40), (75/25) etc. by mass. This experimental study compares the effect of the above-mentioned mixtures to their base constituents and within themselves. [ABSTRACT FROM AUTHOR]

For efficient operation of an air heat pump, it is necessary to take into account the internal conditions of the process and the external conditions of their use. In particular, to calculate the transformation of heat in real nonequilibrium conditions, it is necessary to know the properties of the working substances, their parameters in various states. In order to evaluate all thermodynamic processes of an air heat-cooling system of an air heat pump and make calculations, as a rule, heat diagrams offered by manufacturers are used. As a result of the existing calculation of the theoretical vapor compression cycle, the values of the thermal energy withdrawn by the working fluid during its continuous phase transformation are obtained: boiling, evaporation, condensation, which are determined by the points of the enthalpy state in the corresponding sections of the air heat transfer system circuit. The calculation of the vapor compression cycle is selected according to the given external air conditions, the level of heating of the coolant - water, and the environmentally friendly refrigerant of the air heat pump. The very principle of calculating the cycle of a freon circuit, based on heat transfer due only to phase transitions of the working substance: liquid - vapor-liquid mixture - gas, without analyzing the internal state of the transition process of boiling freon, does not take into account the dynamics and efficiency of the flow. The authors consider practical solutions for the development of mathematical models of heat and mass transfer processes occurring in the evaporation line of an air heat pump (HTP). [ABSTRACT FROM AUTHOR]

In this article widely accepted fact that refrigerants, especially chlorofluorocarbons (R-12 and family) used in present day vapor compression cycles are having a detrimental effect on the earth's upper atmosphere. The United States and most industrialized nations have formally agreed to reduce and ban the production of these chemicals. The automotive air-conditioning industry is greatly affected by this change. Eighty percent of the new cars sold today have on-board air conditioners which are difficult to seal permanently against refrigerant leakage. While most of the industry is concentrating on finding less dangerous forms of chlorofluorocarbons, it must be realized that this would only be a temporary solution. Recent EPA findings show that by 1990 there was cumulative 5% reduction in the ozone layer over the United States. This could, if continued, lead to over 12 million cancer cases and 200,000 deaths over the next 50 years. Energy from the exhaust gas of an internal combustion engine is used to power an absorption refrigeration system to air-condition an ordinary passenger car. [ABSTRACT FROM AUTHOR]

Now a day vapor compression cycle is used for all purpose of cooling technology. The major issues in vapor compression are uneven supply of electricity and the use of environment friendly refrigerant. The absorption refrigeration cycle is one of the alternatives to reduce electric energy demand and the sustainable development. To overcome the problem of low coefficient of performance and to get refrigeration temperature below 0°C, hybrid refrigeration cycle is proposed. In absorption refrigeration system the pressure difference between evaporator –absorber, circulation ratio and the generator temperature are more significant. In hybrid refrigeration system the absorber is at higher pressure than the evaporator which helps not only in increasing the pressure difference between evaporator and absorber but also to achieve low refrigeration temperature. The biggest advantage hybrid cycle is that it can run at low generator temperature. The effect of compression ratio on cycle performance was analyzed. There is an optimum value of compressor ratio up to which the rise of compressor work is less as compared to the rise of ultimate COP. for the hybrid cycle temperature of generator, condenser and evaporator is 90°C, 30°C,-10°C respectively and the optimum value of compressor ratio obtained is 2.5 to 3 [ABSTRACT FROM AUTHOR]

The efficiency of the refrigeration system, can be accomplished by dispersing numerous nanoparticles in the vapor compression refrigeration system's compressor oils and refrigerants, needs to be enhanced with regard to energy protection and environmental considerations. Similarly, the persistent every-day effort in the field of cooling and air- conditioning systems has involved the use of nana-refrigerants/nana-lubricants as one predominant set of applications and with the use of far more efficient eco-friendly fluids.the object of the analysis is to analyzethe effects of nanoparticles being applied to lubricants or refrigerants.this paper describes natural refrigeration fluids (refrigerants) as the perfect refrigeration fluids(refrigerants) that are environmentally sustainable and the ultimate response to ozone depletion and global warming issues. In refrigeration and air conditioning applications, hicks refrigeration fluids (refrigerants) are probably the most famous substitute to cfcs and huffs refrigeration fluids(refrigerants). This paper also explores the impact on tribological efficiency of the dispersion stabilization of nanolubricants and lubrication processes involved in improving tribological performance. Finally, it addresses the obstacles and prospects for future study. [ABSTRACT FROM AUTHOR]

A study of the cycles of a lithium bromide–water absorption chiller with two-stage absorption and three-stage generation of a working substance vapor with an associated mass flow with different supply of the cooling medium to the apparatus has been carried out. The temperature of the heating source necessary for the implementation of the actual thermodynamic cycle of the Lithium Bromide–Water Absorption Chiller (LBWAC) and the most effective thermodynamic cycle has been determined. A comparative analysis of the cycle understudy with the sample cycle (one-stage cycle) LBWAC is carried out. Despite the lower values of the coefficient of performance (COP), the cycle under study provides a doubling of the cooling capacity of the machine, at the same flow rate of the heating source, which is an advantage when the flow rate of the heating source is limited. [ABSTRACT FROM AUTHOR]

The Vapor Compression Refrigeration Cycle is nearly 200 years old, but it does not seem ready to leave the scene any time soon. Vapor compression refrigeration system provides cooling in summer by removing heat and provides heating in winter by adding heat. This is based on reverse engine Carnot cycle. Vapor compression refrigeration cycle is employed in Air- conditioners to cool ambient air temperature in a room. The performance degradation of conventional residential equipment at extreme weather conditions warrants further investigation of the vapor-injection technique. This is focused on the experimental and theoretical investigations of a refrigeration system with an innovative method of vapor injected rotary compressor. Vapor refrigerant injection cycle offers the advantages of more cooling capacity and a better COP than with a conventional cycle. A 1.5 TR vapor compression refrigeration system equipped with a conventional rotary compressor has been built, and tested to serve as a baseline. Unlike the conventional refrigeration system, we additionally use pre-cooler to pre-cool the refrigerant and inject it into the compressor. This enhances the efficiency of the refrigeration system. The baseline versus the improvement on this energy saving system is expected 10-12% using the vapor injection technique. Also we address high ambient operating conditions with the help of Liquid injection. [ABSTRACT FROM AUTHOR]

Vapor compression refrigeration system is commonly used for air-conditioning and refrigeration. It is also used in domestic & commercial refrigerators and cold storage applications. Industrial sectors like refinery, petrochemical, chemical, pharma & pulp also benefit from it. The refrigeration system cools the process fluids to the desired temperature. The most commonly used process fluids are water, air, and brines. Irrespective of size and application of the system, all of them operate on common thermodynamic cycle called 'Vapor compression refrigeration cycle'. Oil is used in compressors of refrigeration systems for lubrication, sealing, cooling, reducing pressure pulsations (leading to silencing effect) and for auxiliary functions like capacity control in screw compressors. Oil gets mixed with refrigerant and is discharged out from the compressor along with refrigerant at high pressure & temperature. Oil, if not separated from the discharge gas, can deteriorate heat transfer in heat exchangers in the refrigeration system. In extreme cases, if oil does not return back to compressor then compressor damage can happen. Therefore, separation of oil from refrigerant before the condenser is important. In this paper the conditions when oil separators are necessary in refrigeration systems are discussed. The paper presents a review of variety oil separation technologies used in different types of refrigeration systems. These technologies are based on fluid flow mechanisms involving velocity reduction, change of direction, gravity settling, centrifugal motion, demister pad, impingement separation and coalescing separation. Every technology has unique advantages and limitations. Construction and operation of commonly used oil separators, employing different technologies for oil separation are explained. Though article focuses on refrigeration systems, the concepts discussed are also applicable to any oil-gas separation systems [ABSTRACT FROM AUTHOR]

The paper presents the theoretical assessment of the energy efficiency of the vapor compression refrigeration cycle based on the compression in the wet vapor region. The estimation is based on the calculation of the compression process in the wet vapor region using the developed mathematical model. The mathematical model is a differential equations system including the equation of the first law of thermodynamics for the wet vapor and Clausius–Clapeyron relation. The assessment of the refrigeration cycle efficiency was based on the numerical solution of the mathematical model in Mathcad. Ammonia was used as the working fluid. The working fluid in the vapor-liquid state is compressed in a low-speed reciprocating compressor. Calculations have shown that compression in the wet vapor region results in decreasing the compression power and consequently in increasing the performance coefficient. [ABSTRACT FROM AUTHOR]

Ensuring the reliable and efficient operation of the reciprocating compressors in the wide range of the operating parameters is one of the important issues at designing, manufacture and operation of the compressor equipment. When designing reciprocating compressors for NGV-refueling compressor station the input pressure can vary from 0.15 to 12.0 MPa depending on the station location. Provision of the compressor serviceability in the wide ranges of parameter variations requires multivariate calculations in order to find the best design parameters of the compressor. The theoretical investigation of the gas initial parameters influence on the multistage reciprocating compressor operation process is represented in this study. Given here is the description of the intermediate pressure calculation method by compressor stages and the real gas properties calculation method. The comparison results of the compressor operation in different modes at compression of both the ideal gas and the real gas. [ABSTRACT FROM AUTHOR]

The use of commonly used vapor compression cycle cold storage in fishing vessel is facing limitations to be widely applied in Indonesian fishermen since it consumes more energy and requires large space. Thermoelectric refrigerator is believed to be a promising option due to its simple design and low energy requirement. However, the Coefficient of Performance (CoP) of the system in current development is relatively low. Although many researches have been conducted to increase the CoP of the system But there is still lack of studies focused on effects of the important variables to cold storage performance. The present study aimed to investigate the effect of input voltage on thermoelectric cold storage chamber temperature in the form of transient behaviors. As a result, it was found that the increase of input voltage significantly affected the cooling performance, although in 6 V input voltage, the result is only a bit lower than 12 V with much lower energy use. In addition, the time needed to get steady state in 12 V was the fastest compared to the other input voltages. Those results can be used as design consideration of a portable thermoelectric cold storage. [ABSTRACT FROM AUTHOR]

The present work deals with vapor compression cycle and methodology for simulation based model in DYMOLA. In this work, the flow through capillary is modeled using Multi-cell model concept and quality at the outlet of the capillary is analyzed for design of evaporator. The study focuses on pressure drop across capillary that affects the flow of refrigerant. The Ordinary Differential Equations are solved to capture the nature of flow. The capillary tube and suction tube in considering brazed condition is considered for modeling purpose. The validation of the developed model is performed using the p-h chart as reported in literature. The results presented in terms of effect of Degree of Subcooling on capillary length and outlet pressure. Furthermore, the study shows the behavior for various parameters such as outlet pressure, pipe thickness and length of pipe and its effect on design parameters. The results are also presented to show the effect of pressure drop in vapor compression cycle for subcooling boundary layer. [ABSTRACT FROM AUTHOR]

The choice of refrigerants for modern air conditioning systems (ACS) of ground-based infrastructure facilities for administrative and general production purposes for the space industry is a multidisciplinary task. In particular, it is necessary to ensure the required energy efficiency of the refrigeration cycle, environmental safety of the production, operation and disposal of the refrigeration unit. An operating pressure levels in the cycle affect the availability, cost and safety of refrigeration equipment. Fire safety of the working fluid is also important. The history of the issue of environmental protection from emissions of refrigerants causing the destruction of the ozone layer and the greenhouse effect is considered. The restrictions implemented by existing agreements on the use of refrigerants are described. The existing criteria for evaluating the refrigerant in terms of environmental friendliness are described. A brief description of the properties of carbon dioxide (CO2) and dimethyl ether (DME) is given, the key features of which are the high-pressure range and temperature glide in the case of CO2 and the cost effectiveness, environmental friendliness and fire safety in case of DME. The possibility of using a mixture of CO2 and DME in the framework of a vapor-compression refrigerating cycle is considered. Comparative calculations of vapor compression cycles were carried out both for pure DME, R22 and R410A, and for a mixture of DME and CO2 at various concentrations. Comparisons are made between the proposed mixture and the refrigerants widely used before the introduction of the protocols (R22 and R410A) for operating pressures. Also made a comparison of the coefficient of performance of the proposed mixture at various concentrations of its components in the selected range. An interval in which the use of the proposed mixture is most optimal from the point of view of refrigerating capacity has been identified. [ABSTRACT FROM AUTHOR]

Modern design technologies are linked with the calculations by the finite element method, finite volume method and other methods that require powerful data processing, which is typical for high-tech productions in the space industry. Such calculations are no longer possible for personal computers and require specialized computing centres (CC). For stable all-year CC operation, reliable engineering support, which includes all-year air conditioning systems (ACS) with a given level of reliability is necessary. There are several traditional methods for CC cooling: by close control units (CCU) based on vapor compression refrigeration machines (VCRM), chiller systems with an intermediate thermostating liquid. However, nowadays, when the computing centres’ power increases every year, the requirements for energy efficiency of such systems becomes tougher, there is a need to find new, more energy efficient and at the same time environmentally friendly solutions for computing centres cooling. To solve this problem, the existing cooling systems were analyzed and the most appropriate one was chosen. The calculation was made for the existing CC located in Moscow, with a heat load of 100 kW. A comparison of the systems showed that the proposed system consumes 2.5 times less energy than the close control unit and 2 times less than the chiller-fan coil system. [ABSTRACT FROM AUTHOR]

The current vapor compression cycle has been extensively applied in air conditioning systems. However, there continue to be some problems that occur in its use, such as arising from the impact of the use of synthetic refrigerants that result in the depletion of the ozone layer and global warming, adds heavy load of the vehicle and consumes considerable energy. This study will examine a vapor compression refrigeration cycle with an internal phase-separating loop (ILP-VCC) to improve the performance of a zeotropic R290 / R600a hydrocarbon mixture in an air conditioning system compared with R134a. Some system performance parameters studied carefully include refrigerant charge, compressor work, working pressure, electric energy consumption and COP. As comparisons, the performances of conventional vapor compression refrigeration cycle (C-VCC) using R134a and using R290/R600a blend were also tested. The results show that R290/R600a mixture reduces the refrigerant charge by 52.2% and decreases the compressor work by 4.87% and gives a higher COP compared to R134a. In the ILP-VCC R290/R600a mixture provides an increased volumetric cooling capacity of 6.6% and an increase of 6.63% in COP compared to that in C-VCC. [ABSTRACT FROM AUTHOR]

Occording to US Department of Energy, up to 39% of the world’s energy reserve is consumed by buildings and up to 52% is contributed by the use of HVAC system. An adsorption system that use physical adsorbent such as silica gel and zeolite with water pairing is used to produce cooling making vapor compression system no longer be used. It will no longer need refrigerants so it will be more energy efficient and environmentally friendly. There are some drawbacks in using adsorption system such as low COP which needs more optimization to make it perform better. The adsorption chiller will be able to produce a higher cooling power at a higher hot water inlet. Using the genetic algorithm optimization technique, it is found that the best control mechanism for this system is 781, 34, and 34 seconds for adsorption, mass recovery, and heat recovery time respectively. [ABSTRACT FROM AUTHOR]

The ease of manufacture and cheap price of capillary tubes made their usage as the throttling means in most portable freezing and air conditioning devices. In this experimental study, capillary tubes of diameters 0.9, 1.2 & 1.4 mm are employed at different evaporator loads with R-12 as refrigerant to evaluate the performance of refrigerator. It is The compressor work required is less in case of 0.9mm diameter capillary tube noticed that the COP is comparatively good for VCR with 0.9mm diameter capillary tube and also the Compressor work required at 17kg evaporator load with 0.9mm diameter capillary tube is 25kW whereas with 1.2mm and 1.4mm diameter capillary tubes it is 30kW and 31 kW respectively. [ABSTRACT FROM AUTHOR]

Air-Conditioning systems based on vapor compression system consuming a lot of energy. Meanwhile, Valeriy Maisotsenko has improved evaporative cooling system where just consume a small amount of fan power. The resulting cycle is called as Maisotsenko Cycle where dew point as the limitation rather than wet bulb temperature. This developed the dew point cooling system with very low power consumption. The aims of this project are to identify dew point cooling system suitability for cooling at high humidity region, to find a solution at high humidity region and to stimulate temperature distributions in a small room that equipped with the dew point cooling system. [ABSTRACT FROM AUTHOR]

Every year, the ecological and economic requirements to the working substances of refrigeration units are being toughened, new freons of vapor compression refrigerators are being sought and alternative cooling methods are being searched for. One of the variants of the evolution of refrigerators is the possibility of using magnetocaloric coolers, with a working range near room temperatures. Based on the analysis of information on existing magnetic coolers, their classification was carried out and their main features were identified. One of the most important components of the magnetocaloric cooler is the magnetic system. In this article, the requirements for the magnetic system and the working body are considered. The scheme of the magnetic system is chosen. The simulation of the magnetic system in the ANSYS software environment is carried out. The law of change of a magnetic field in a working body for the chosen method of change of a magnetic field is obtained. [ABSTRACT FROM AUTHOR]

Refrigeration and air conditioning is an active and a rapidly developing technology. Refrigeration is the process of removing heat from low temperature reservoir to high temperature one. Meanwhile air conditioning is the process of removing heat from the interior of an occupied space to improve the comfort of occupants. There are many systems in refrigeration and air conditioning. The most popular and widely used is vapor compression refrigeration system for daily applications. The working fluids used in the vapor compression refrigeration system are called refrigerants. One of components refrigeration system is evaporator. The evaporator removes heat of the area to be cool. The current of the vapor compression refrigeration system has a constant speed of motor fan on the evaporator. The effects of the constant speed of the motor, system are on the stable. In this project, design of system is combined with Arduino Atmega 2560. The motor fan of evaporator will be controlled by using Arduino Atmega 2560. The controlling uses two methods, Conventional (On-Off) and Variable Speed Drive (VSD) based on temperature setting. This affects the electrical consumption, cooling time, and coefficient of performance (COP) of the system. The result shows that the variable speed drive (VSD) for the cooling time has 3.9 minutes for temperature setting 22°C and 2 minutes for 24°C, those values are better than the conventional control. The power consumption of the variable speed drive (VSD) is 1.430 kWh and 1.248 kWh which is better than that of the conventional control. [ABSTRACT FROM AUTHOR]

Storage space requirements with a large refrigeration capacity they use refrigerants types R22 and R404A. This research to develop alternative technologies to meet the needs of storage space with a large refrigeration capacity. Liquid suction subcooling technology is typically used to obtain improve refrigeration effect at vapor compression refrigeration system. Liquid suction heat exchanger subcooling used a type of tube in tube heat exchanger installed between the condenser and the capillary tube before entering the evaporator. Refrigerant used in this research is R22, R404A, and mixture refrigerant R290/R600a [50:50]. In steady state condition with subcooling temperature evaporator with R290/R600a lower reaches -30°C, lower than R404a and R22 is -24°C and -22°C. Liquid suction heat exchanger subcooling effect on △Tsub. The cooling effect by the mixture refrigerant of R290/R600a greater than R404a and R22, and liquid suction heat exchanger increase refrigeration capacity index (RCI). The average increase in RCI respectively 3.91%, 7.78%, and 11.87%. Work compressor and compressor work index (CWI) with a mixture refrigerant of R290/R600a greater than R404a and R22, the average work compressor and the working compressor index is greatest mixture refrigerant R290/R600a. CWI respectively is an average of 5.68%, 8.82%, and 11.82%. The average COP, their liquid suction heat exchanger, respectively are 3.38, 3.18 and 2.63. COPRS with a mixture refrigerant of R290/R600a [50:50] is bigger than the R22 and R404a, and the average COPRS is 5:01%, 5.95%, and 7:41%. A mixture refrigerant R290/R600a [50:50] have the same characteristics as R404a, which can be used as a substitute for refrigerant R22 and R404A. [ABSTRACT FROM AUTHOR]

The aim of this work was to determine the effects of water temperature and air stream velocity on the performance of direct evaporative air cooler (DEAC) for thermal comfort. DEAC system requires the lower cost than using vapor compression refrigeration system (VCRS), because VCRS use a compressor to circulate refrigerant while DEAC uses a pump for circulating water in the cooling process to achieve thermal comfort. The study was conducted by varying the water temperature (10°C, 20°C, 30°C, 40°C, and 50°C) at different air stream velocity (2,93 m/s, 3.9 m/s and 4,57 m/s). The results show that the relative humidity (RH) in test room tends to increase with the increasing of water temperature, while on the variation of air stream velocity, RH remains constant at the same water temperature, because the amount of water that evaporates increase with the increasing water temperature. The cooling effectiveness (CE) increase with the increasing of air stream velocity where the higher CE was obtained at lower water temperature (10°C) with high air velocity (4,57m/s). The lower room temperature (26°C) was achieved at water temperature 10°C and air stream velocity 4.57 m/s with the relative humidity 85,87%. DEAC can be successfully used in rooms that have smoothly air circulation to fulfill the indoor thermal comfort. [ABSTRACT FROM AUTHOR]

A performance analysis based on exergetic performance coefficient (EPC) criterion was carried out for a dualevaporator vapor compression refrigeration system. The influence of the condensing and evaporating temperature on the EPC, the coefficient of performance (COP), the second law efficiency and the destruction of exergy will be presented. It is found that the evaporating and condensing temperatures have strong effects on EPC in the system. Condensing temperature increases will decrease EPC, COP, and second law efficiency, while evaporating temperature increases will increase the EPC, COP, and second law efficiency. The EPC increases and the total exergy destruction decreases with decreasing temperature difference between the evaporator and refrigerated space and between the condenser and ambient temperature. The EPC can be used for selection of optimal design parameters and the procedures given in this paper for exergy analysis of a dual evaporator vapor compression refrigeration systems has been applied to actual systems. [ABSTRACT FROM AUTHOR]

Storage space requirements with a large refrigeration capacity they use refrigerants types R22 and R404A. This research to develop alternative technologies to meet the needs of storage space with a large refrigeration capacity. Liquid suction subcooling technology is typically used to obtain improve refrigeration effect at vapor compression refrigeration system. Liquid suction heat exchanger subcooling used a type of tube in tube heat exchanger installed between the condenser and the capillary tube before entering the evaporator. Refrigerant used in this research is R22, R404A, and mixture refrigerant R290/R600a [50:50]. In steady state condition with subcooling temperature evaporator with R290/R600a lower reaches -30°C, lower than R404a and R22 is -24°C and -22°C. Liquid suction heat exchanger subcooling effect on ΔTsub. The cooling effect by the mixture refrigerant of R290/R600a greater than R404a and R22, and liquid suction heat exchanger increase refrigeration capacity index (RCI). The average increase in RCI respectively 3.91%, 7.78%, and 11.87%. Work compressor and compressor work index (CWI) with a mixture refrigerant of R290/R600a greater than R404a and R22, the average work compressor and the working compressor index is greatest mixture refrigerant R290/R600a. CWI respectively is an average of 5.68%, 8.82%, and 11.82%. The average COP, their liquid suction heat exchanger, respectively are 3.38, 3.18 and 2.63. COPRS with a mixture refrigerant of R290/R600a [50:50] is bigger than the R22 and R404a, and the average COPRS is 5:01%, 5.95%, and 7:41%. A mixture refrigerant R290/R600a [50:50] have the same characteristics as R404a, which can be used as a substitute for refrigerant R22 and R404A. [ABSTRACT FROM AUTHOR]

The aim of this work was to determine the effects of water temperature and air stream velocity on the performance of direct evaporative air cooler (DEAC) for thermal comfort. DEAC system requires the lower cost than using vapor compression refrigeration system (VCRS), because VCRS use a compressor to circulate refrigerant while DEAC uses a pump for circulating water in the cooling process to achieve thermal comfort. The study was conducted by varying the water temperature (10°C, 20°C, 30°C, 40°C, and 50°C) at different air stream velocity (2,93 m/s, 3.9 m/s and 4,57 m/s). The results show that the relative humidity (RH) in test room tends to increase with the increasing of water temperature, while on the variation of air stream velocity, RH remains constant at the same water temperature, because the amount of water that evaporates increase with the increasing water temperature. The cooling effectiveness (CE) increase with the increasing of air stream velocity where the higher CE was obtained at lower water temperature (10°C) with high air velocity (4,57m/s). The lower room temperature (26°C) was achieved at water temperature 10°C and air stream velocity 4.57 m/s with the relative humidity 85,87%. DEAC can be successfully used in rooms that have smoothly air circulation to fulfill the indoor thermal comfort. [ABSTRACT FROM AUTHOR]

A performance analysis based on exergetic performance coefficient (EPC) criterion was carried out for a dualevaporator vapor compression refrigeration system. The influence of the condensing and evaporating temperature on the EPC, the coefficient of performance (COP), the second law efficiency and the destruction of exergy will be presented. It is found that the evaporating and condensing temperatures have strong effects on EPC in the system. Condensing temperature increases will decrease EPC, COP, and second law efficiency, while evaporating temperature increases will increase the EPC, COP, and second law efficiency. The EPC increases and the total exergy destruction decreases with decreasing temperature difference between the evaporator and refrigerated space and between the condenser and ambient temperature. The EPC can be used for selection of optimal design parameters and the procedures given in this paper for exergy analysis of a dual evaporator vapor compression refrigeration systems has been applied to actual systems. [ABSTRACT FROM AUTHOR]

In this paper, a set of heat pump (called as Mechanical Vapor Recompression, MVR) propelled by a centrifugal fan is tested and it shows some special characteristic when it works together with a falling film evaporator. Firstly, an analysis of the fan's suction and discharge parameters at stable state, such as its pressure and temperature, indicates that a phenomenon of wet compression is probably to appear during vapor compression. As a result, superheat after saturated vapor is compressed is eliminated, which reduces discharge temperature of the system. It is because drops boil away and absorb the super heat into their latent heat during vapor compression. Meanwhile, drops in the suction vapor add to the compressed vapor, which increase the given heat of the MVR heat pump. Next, assistant electric heat could adjust and keep steady of the operating pressure and temperature of an MVR heat pump. With the evaporation temperature up to be high, heat balance is broken and supplement heat needs to increase. Thirdly, the performance of an MVR heat pump is affect by the balance of falling film and evaporation that has an effect on heat transfer. Then, two parameters standing for the performance are measured as it runs in practical condition. The two important parameters are consumptive electricity power and productive water capacity. According to theoretical work in ideal condition by calculation and fan's input power by measure as running, adiabatic efficiency (ηad) of a centrifugal fan is calculated when it is applied in a heat pump of MVR. Following, based on ηad, practical SMER and COP of an MVR heat pump are discovered to be correlative with it. Finally, in dependence on productive water in theory and in practice, displacement efficiency (ηv) of centrifugal fans is obtained when compressing vapor, and so provide some references of matching a fan for an MVR heat pump. On the other hand, it is helpful to research and develop MVR heat pumps, and also to check electricity power consumption while operating practically in light of electric motor efficiency (ηe) and ηad. [ABSTRACT FROM AUTHOR]

The vapor-compression cycle for refrigeration near ambient temperature achieves high efficiency because the isenthalpic expansion of the condensed liquid is a rather efficient process. However, temperatures are limited to about 200 K with a single-stage system. Temperatures down to 77 K are possible with many stages. In the case of microcryocoolers using microcompressors, pressure ratios are usually limited to about 6 or less. As a result, even more stages are required to reach 77 K. If the microcompressors can be fabricated with low-cost wafer-level techniques, then the use of many stages with separate compressors may become a viable option for achieving temperatures of 77 K with high efficiency. We analyze the ideal thermodynamic efficiency of a cascade Joule-Thomson system for various temperatures down to 77 K and with low pressure ratios. About nine stages are required for 77 K, but fewer stages are also analyzed for operation at higher temperatures. For 77 K, an ideal second-law efficiency of 83 % of Carnot is possible with perfect recuperative heat exchangers and 65 % of Carnot is possible with no recuperative heat exchangers. The results are compared with calculated efficiencies in mixed-refrigerant cryocoolers over the range of 77 K to 200 K. Refrigeration at intermediate temperatures is also available. The use of single-component fluids in each of the stages is expected to eliminate the problem of pulsating flow and temperature oscillations experienced in microcryocoolers using mixed refrigerants. [ABSTRACT FROM AUTHOR]

This paper introduces the working principle and system constitution of the linear Fresnel solar lithium bromide absorption refrigeration cycle, and elaborates several typical structures of absorption refrigeration cycle, including single-effect, two-stage cycle and double-effect lithium bromide absorption refrigeration cycle A 1.n effect absorption chiller system based on the best parameters was introduced and applied to a linear Fresnel solar absorption chiller system. Through the field refrigerator performance test, the results show: Based on this heat cycle design and processing 1.n lithium bromide absorption refrigeration power up to 35.2KW, It can meet the theoretical expectations and has good flexibility and reliability, provides guidance for the use of solar thermal energy. [ABSTRACT FROM AUTHOR]