Refrigerants

— In the present study, recent research is considered about new generation refrigerant R-1234yf and R-1234ze (E).
Chlorofluorocarbons (CFCs) had been phased out under the Montreal Protocol; CFC alternative refrigerants are searching for based on
the condition of no chlorine atoms because of zero ODP. It seemed that conversion from CFC refrigerant to HFC refrigerant or natural
refrigerant had progressed smoothly in the two decades. As for the low GWP refrigerants, hydrofluoric-olefins (HFOs), especially, HFO-
1234yf (CF3CF=CH2: 2, 3, 3, 3-tetrafluoropropene) and HFO-1234ze (E) (CF3CH=CHF: trans-1, 3, 3, 3-tetrafluoropropene) are
recently focusing in the world. Both of these HFOs have low GWP values (HFO- 1234yf is 4 and HFO-1234ze (E) is 6), and expecting as
the next generation refrigerant. R-1234yf and R-1234ze (E) can used in mobile air conditioning and ejector refrigeration system.

The capillary tube used mostly in the refrigerant flow control devices. Hence performance of the capillary tube should be good for smooth refrigerant flow. Many researchers worked in these area by experimentally and analytically. In this present work analyse the flow analysis of the refrigerant inside a capillary tube for adiabatic flow conditions. The proposed model has predict flow characteristics in adiabatic capillary tubes for a given mass flow rate. In the current work R-22 is replaced by Ammonia refrigerant has been used as a working fluid inside the capillary tube and the capillary tube design is changed straight to coiled capillary, which taken from good literature. The analysis is done in ANSYS CFX 16.2 software. It is observed from the results dryness fraction by using the helical capillary tube (Ammonia refrigerant flow) is better than straight and existing helical capillary tube (R22 refrigerant flow). The best suitable helical coiled design is suggested.

This study was conducted to investigate the status of domestic refrigerators available in Bangladesh. At present more than 50 refrigerator brands are available in Bangladesh. Almost all of the brands are Chinese using aluminum compressors and low quality refrigerants. These are cheaper than any well-known refrigerator brand. The common complains of the consumers were delayed ice formulation and noise. R12, R22, R134a, R600 and R600a were commonly used as refrigerants in Bangladesh which required 24, 34, 48, 72 and 96 minutes respectively to make ice. Their refilling costs and noise level were 1350, 500, 1350, 1000, 2200 Tk/L and 80, 81, 72, 82, 96 db respectively. R12 and R22 formed hard ice within 24 and 34 minutes respectively but R134a, R600, R600a could not form ice so quickly. The noise level, refilling cost and complains of R600 and R600a were high from both consumers and repairers. Noise level also varied upon compressor. Repairers feel comfort to refill R12, R22 and R134a instead of R600 and R600a, though R12, R22 are banned in many countries according to the declaration of Montreal Protocol and Kyoto protocol. Conventional refrigerators could not be run by R600a, the most eco-friendly refrigerant as because it makes huge noise. So repairers refill the conventional refrigerators with R12, R22 and R134a. R134a is better than R600/R600a and tends to be eco-friendly refrigerant.

This article compares climate impacts of two heat-pump systems for domestic heating, that is, energy consumption for space heating of a residential building. Using a life cycle approach, the study compared the energy use and greenhouse gas (GHG) emissions of direct electric heating, a conventional air-source heat pump, and a novel ground-source air heat pump innovated by a citizen user, to assess whether such user innovation holds benefit. The energy use of the heat pumps was modeled at six temperature intervals based on duration curves of outdoor temperature. Additionally, two heat pump end-of-life scenarios were analyzed. Probabilistic uncertainty analysis was applied using a Monte Carlo simulation. The results indicated that, in ideal conditions, that is, assuming perfect air mixing, the conventional air-source heat pump’s emissions were over 40% lower and the ground-air heat pump’s emissions over 70% lower than in the case of direct electric heating. Although proper handling of the refrigerant is important, total leakage from the retirement of the heat-pump appliance would increase GHG emissions by just 10%. According to the sensitivity analysis, the most influential input parameters are the emission factor related to electricity and the amount of electricity used for heating.

In our aim is enhancing the efficiency of industrial air conditioning system with nano particle to increase the coefficient of performance. Due to the increase in machine technology and there is a lot of new innovation of air conditioner and its components, to make sure the proper running of machinery system, air conditioner and its cooling system. In this work planned to build a chilled water air conditioning system (HVAC) to reduce the improper working of the air conditioner which required cooling. This chiller plant is play a major role in these works and its benefits. This chiller plant system can used in the required places and reduce the power consumption. To avoid the environmental issue the water is flowing through the inside the air conditioner system to make sure the cooling water temperature. Introducing a ZnO as the nano particle, this nano particle have a good thermal conductivity, the heat transfer of the chiller plant system increases when the use of nano particle. The system has been running for certain period and it can be in off state for a certain period of time after it reaches the temperature range, to reduce the power consumption and the maintenance of the chiller plant. Experimental result indicates the comparative performance of the chilled water air conditioning system with and without use of nano particle which increase the 22% C.O.P of the system. Keywords: Chilled water air conditioning system, Nanoparticle, Zinc oxide(ZnO), Refrigerant(R22), Chiller, Nano fluid, Coefficient Of Performance. I. INTRODUCTION As a result of the multiple applications of chilled water air conditioning systems especially in large zones designs, needs to more savings in energy resources which need unconventional creatively ideas to enhance the system performance with a reduction in consuming power. Poor thermal characteristics of traditional fluids such as water, oil, glycerine, ethylene glycol and other liquids give a challenge to there searchers to enhance its thermal properties to rapid the heat transfer rate per unit time. Nanotechnology is a revolution in the field of technology and was exploited for several applications in industry, medicine, and agriculture. Nanoparticles are produced by reduction its size to less than 100 nm which has a unique favourite property to be applied. Nano-metals are added to the conventional fluid to form what is called nanofluid. Nanofluids are embedded suspensions enclosing nanoparticles of less than 100 nm in traditional base fluids. Nanofluids offer higher thermofluid properties compared to traditional base fluids. Nanofluids gain higher thermal conductivity which enhances the performance of heat transfer equipment. The improvement of heat transfer by nanofluids could be compacting the design of heat exchangers and hence reduction in cost. Because of the air conditioners consume about 40-50% of the total electric power of the air-conditioned zones, it has become a fertile field in front of researchers to seek alternatives to reduce the consumed power rates. So, several studies have been exploited the nanofluid significant thermal effect due to their energy efficiency in the engineering applications. Nanoparticles can be utilized in an expansive scope of improving the HVAC systems performance because of their improved both heat transfer rate and energy efficiency. The present investigation is concerned to study the performance characteristics of the vapour compression refrigeration cycle associated with a chilled water air conditioning system using nanofluid. The influence of nanofluid concentration ratio, nanoparticle type and nanofluid volumetric flow rate on the performance characteristics are discussed with comparing to pure water as the working fluid of a chilled water air conditioning system. The hybridization is improving the thermofluid properties that strongly depended on the mixture ratios and consequently changes in other physical properties. This emphasizes the importance of studying the performance characteristics of the vapor compression refrigeration cycle integrated with a chilled water system in the case of pure water, nanofluid. From this point, the current work examines the effect of the concentration ratio of nanomaterials on the performance of an air conditioning system associated with a chilled water system.

The aim of this paper is to examine the COP
and the applicability of certain refrigerants, which are
used today in refrigeration systems, such as R410A,
R404A and R407C. Special attention was given to
refrigerants R134a and R1234yf. Because of the higher
GWP (1430) of the R134a, researches have begun in a
world scale, which of the cooling agents could serve as a
substitute. In the USA it has been announced that from
2017 the R1234yf will be in use for automobile air
conditioning systems, instead of the R134a. However
Mercedes has proved that the use of R1234yf is dangerous
due to flammability. In addition R1234yf has lower COP
compared to R134a refrigerant. Due to the flammability
and lower values of COP, R1234yf cannot replace the
R134a in heat pumps. It should be used in very low power
refrigerators only, because of small quantities.

Through the application of the fi rst and second laws of thermodynamics upper and lower limits for the coefficient of performance (COP) of absorption cooling cycles are derived. These upper and lower limits, besides being dependent on the environmental temperatures of components of the cycle, are also dependent on the thermodynamic properties of refrigerants, absorbents, and their mixtures. With the use of these upper and lower limits of COP it is now possible to make a quantitative comparative study of different refrigerant-absorbent combinations. The technique developed is applied for the comparative evaluation of NH3 + H2O, NH3 + NaSCN and H2O + LiBr combinations which are the favorable candidates used in solar absorption cooling cycles.

This paper presents a test rig to measure the dynamic heat transfer coefficient of the refrigerant R-134a in a small diameter horizontal pipe. The experiment layout is basically a cooling cycle. The basic components are a receiver tank filled with R-134a, a pump, an evaporator pipe and a condenser. The evaporator pipe made out of copper is the main element. Thermocouples, pressure sensors and a mass flow sensor provide the information necessary to determine the heat transfer coefficient of the horizontal pipe. In addition to the experimental investigations, a numerical model is created. The results are compared with the test rig results to validate the numerical model.

This paper presents a study of pressure drops during condensation inside a smooth, an 18-deg helical microfin, and a herringbone microfin tube. Measurements were conducted with refrigerant flowing through the tube of a concentric heat exchanger, with water flowing in a counterflow direction in the annulus. Each tube was part of a condenser consisting of eight subcondensers with instrumentation preceding each subcondenser. Three refrigerants were used, namely, R-22, R-407C, and R-134a, all operating at a saturation temperature of 40 °C with mass fluxes ranging from 400 to 800kg/m2 s. Inlet qualities ranged from 0.85 to 0.95 and outlet qualities ranged from 0.05 to 0.15. The test results showed that on average for the three refrigerants the pressure gradients of the herringbone microfin tube were about 79% higher than that of the smooth tube and about 27% higher than that of the helical microfin tube. Further, a correlation from the literature for predicting pressure drops inside a he...

The present paper deals with the study of system uses "Thermoelectric cooling module" which works on thermoelectric refrigeration, aims to produce cooling by exploitation electricity result that states that once D.C voltage is applied over 2 junctions of variant electrical conductors, Endothermic reaction usually takes place in one junction and warmth is rejected at another junction which creates a temperature variation. Thermoelectric cooling systems have blessings over standard cooling devices, like compact in size, lightweight in weight, high responsibility, no mechanical moving elements and no operating fluid. The present airconditioning system produces cooling result by refrigerants like Freon, Ammonia, etc. mistreatment these refrigerants will get most output however one amongst the key disadvantages is harmful gas emission and warming. These drawback is overcome by mistreatment thermo electrical modules (Peltier effect) air-conditioner.

With the recent government organization and regulation for saving the water, trees, curtains to the use of these sources which contribute to global warming present day mankind uses various equipment in their daily need which includes conventional cooler, AC etc. This consumes large amount of water and electricity so for reducing the use of these main sources research involves the use of VCRS system which include eco-friendly refrigerant R134a in cooler system. This system is mounted in the research model in a proper manner so that it is compact in size. The refrigerant R134a absorbs the heat from air and makes the air cooled, itself getting vaporized in evaporator and then the cooled air is sent outward from the opening. In the research model with help of fan running on motor and gives the cooling effect. This use of VCRS system with eco-friendly refrigerant reduces the consumption of the water, electricity consumption and tree which is used for making wood wool in conventional cooler. This ultimately reduces the global warming. For making these purposes the project is developed.

Due to the increase in energy prices and spiralling consumption, there is a need to greatly reduce the cost of electricity within data centers, where it makes up to 50% of the total cost of the IT infrastructure. A technological solution to this is using on-chip cooling with a single-phase or evaporating liquid to replace energy intensive air-cooling. The energy carried away by the liquid or vapor can also potentially be used in district heating, as an example. Thus, the important issue here is “what is the most energy efficient heat removal process?” As an answer, this paper presents a direct comparison of single-phase water, a 50% water–ethylene glycol mixture and several two-phase refrigerants, including the new fourth generation refrigerants HFO1234yf and HFO1234ze. Two-phase cooling using HFC134a had an average junction temperature from 9 to 15 °C lower than for single-phase cooling, while the required pumping power for the central processing unit cooling element for single-pha...

A recently built experimental setup for determination of solid–liquid equilibria was slightly modified. The action taken on the existing system focused on correcting the drawbacks of the cooling system. In this version of the setup, a direct liquid nitrogen supply was preferred. By means of the modified apparatus, solid–liquid equilibria of the CO2 + R143a and N2O + R143a binary systems were studied. The triple point of R143a was measured to check the reliability of the modified apparatus, revealing good consistency with the literature. The system’s behavior was measured down to temperatures of 148 K. The results obtained for the mixtures were interpreted by means of the Schröder equation.

This paper presents an improved flow pattern map for predicting the heat transfer coefficients during condensation of R-134a inside a smooth horizontal tube. Experimental tests were conducted over the low-mass flux range of 75–300 kg/m2 s, at a nominal saturation temperature of 40 °C, and with the test section vapour qualities ranging from 0.76 down to 0.03. This represents points within the annular, intermittent and stratified flow regimes. The results were used to modify the Thome–El Hajal flow pattern map to include a transition region between the stratified-wavy and annular or intermittent flow regimes. The revised flow pattern-based heat transfer correlation predicted the experimental data to a mean deviation of less than 6%.

Hydrocarbons being natural fluid have drawn much attention of the scientists and researchers for the application as a sustainable material for the vapor compression refrigeration system. This paper presents a comparison of the energetic and exergetic performances of a domestic refrigerator using pure butane and isobutane as refrigerants. The thermodynamic performances such as exergy destruction or losses, exergy efficiency, and coefficient of performances (COP) were investigated. These parameters were measured at varied operating conditions. Exergy and energy efficiencies of isobutane were found to be 50% and 175% higher than that of R-134a. The analysis shows that the performances of butane and isobutane as refrigerants are comparable with HFC134a. It has also been found that at higher evaporating temperatures, the exergy losses are minimal. The maximum exergy loss occurred in the compressor and the value was 69% of the whole losses in the system. Highest sustainability index was found for butane compared to that of R134a and R600a, respectively. Copyright © Taylor & Francis Group, LLC.

http://www.tandfonline.com/doi/pdf/10.1080/15435075.2011.621491

A low cost and indigenous experimental training, testing and process optimization setup of the heat pumping system is designed, developed and fabricated for the engineering students. The setup can be an effort to provide an indigenous option and import substitution for the local industries and academic institutions. The system uses difluoro-monochloromethane (CHCIF2) for the heat transport mechanism which has a heat of vaporization (∆Hvap) of 233.95 kJ/kg at the boiling point of-40 o C. The control compression and expansion of the gas is performed by using the electro-mechanical controls and semi-hermetic compressor. The whole experimental setup is installed on the bench top table with vertical installation in open-air inside the laboratory. The change in pressure and temperature values at various stages of the setup is monitored by sensors, gauges, and visual displays. Physical states of the transport medium, i.e. liquid, vapors and super vapors are monitored by installing the transparent glass windows in the passage of transport medium. Hands-on experiments and procedures can be run on this setup in order to acquire deeper knowledge about design and process optimization of thermodynamical parameters, such as coefficient of performance (COP), Carnot cycle, dynamics of pressure-temperature imbalance during operating cycles and phase transformation of the transport medium under several operating conditions and parameters.

Adsorption cooling systems are considered as energy efficient and sustainable technologies from the perspective of environmental safety and thermal energy utilization. These systems possess zero potentials of ozone depletion and global warming. In adsorption cooling processes, knowledge of adsorbent-refrigerant pairs (e.g. adsorption equilibrium, kinetics and heat) is important. The system performance is directly related to interactions between the adsorbent and refrigerant. Thus, the overall thermodynamic performance of the system can be improved accordingly. In this study, numerous carbon based adsorbents are explored in detail with different types of refrigerants (e.g. ethanol, methanol, CO2, R134A etc.). In order to select the optimum adsorbent-refrigerant pair. The analyses in the study are based on the experimental data on various adsorbent-refrigerant pairs available in the literature. Various adsorption isotherms models including: Dubinin-Astakhov, Tóth, Freundlich etc. present adsorption equilibrium data. Consequently, overall system analyses have been conducted by means of pressure-temperature-adsorption equilibrium (P-T-W) diagram. The P-T-W diagram is also drawn from the ideal cycle analysis in order to explain the performance of adsorption cooling systems. The coefficient of performance of the system has been calculated accordingly for the studied adsorbent-refrigerant pairs.