Class Of Refrigerants Research Articles

Experimental investigation on VCRS by using R-134a and R-410a of air and evaporative cooled condenser

In this study, experimental research is carried out on two different class of refrigerants at three varied ambient conditions viz. (30°C, 35ºC and 40ºC) and three different air velocities viz. (1.25, 1.00, 0.75 m/s) in air cooled and evaporative cooled condenser. The first class is of low temperature refrigerant (R-134a) and the second is of high temperature refrigerant (R-410a). The results described that COP of high temperature refrigerant is greater than that of low temperature refrigerant. The COP increased with increasing air speed in air cooled and evaporative cooled condenser and decreased with increasing the ambient temperatures. For a fixed ambient temperature and air velocity, the COP of R-410a turned out to be greater than the COP of R-134a.Thus proving that high temperature refrigerant is better in performance than low temperature refrigerant.

Bill would authorize U.S. reduction of HFCs

Manufacturers of hydrofluoroolefins (HFOs), a new generation of refrigerants that have very low potential to cause global warming, are getting a boost from the U.S. Congress. Republicans and Democrats in the Senate are backing a bill (S. 2448) that would authorize EPA to ratchet down the production of hydrofluorocarbons (HFCs), a class of refrigerants that are potent greenhouse gases. HFOs are beginning to replace HFCs in vehicle air conditioners, store refrigerators, and vending machines. EPA restricted the use of HFCs and refrigerant blends containing HFCs in a 2015 rule. But Mexichem Fluor and Arkema, which make HFC-134a (1,1,1,2-tetrafluoroethane), challenged the regulation. HFC-134a has long been used as a refrigerant in car air conditioners. A federal court sided with the two companies last year. It faulted EPA for basing the regulation on part of the Clean Air Act authorizing the agency to require replacement of compounds that deplete stratospheric ozone with

Refrigerants and environment

The refrigeration and air-conditioning industries are important sectors of the economy and represents about 15 % of global electricity consumptions. The chlorofluorocarbons also called CFCs are a class of refrigerants containing the halogens chlorine and/or fluorine on a carbon skeleton. Because of their environmental impact the Montreal Protocol was negotiated in 1987 to limit the production of certain CFCs and hydrochlirofluorocarbons (HCFCs) in developed and developing countries. The halogenated refrigerants are depleting the ozone layer also major contribution to the greenhouse effect. To be acceptable as a refrigerant a fluid must satisfy a variety of thermodynamic criteria and should be environment friendly with zero Ozone Depletion Potential and low Global Warming Potential. The perspective of a future phase down of HFCs is considered in this report taking into account a strategy for the phase out of HCFCs and perspective of choosing of various refrigerant followed by safety issues.

Fluid-phase-equilibrium prediction of fluorocompound-containing binary systems with the predictive E-PPR78 model

In order to reduce the overall emissions of greenhouse gases and to be in compliance with the current environmental regulations, a new class of refrigerants has appeared. Such refrigerants are generally multi-component systems that contain a fluorocompound mixed with CO2 and/or an alkane. In order to design processes involving such blends or to implement a product-design approach aimed at identifying new refrigerant mixtures, an equation of state (EoS) able to predict the properties of fluorocompound-containing systems is required. In order to reach this goal, it was decided in this study to add six fluorinated groups to the Enhanced-PPR78 model which combines the Peng–Robinson EoS and a group contribution method aimed at estimating the binary interaction parameters, kij(T), involved in Van der Waals one-fluid mixing rules.

Insights into the next generation HVAC&R refrigerant future

Prospects for policy and regulatory actions to reduce, restrict, and even eliminate the use of today's hydrofluorocarbon refrigerants continue to exist and grow because of their relatively high global warming potentials and consequent impact on climate. These regulatory actions are leading to the development and investigation of a new class of refrigerants, unsaturated chlorinated and fluorinated hydrocarbons, with lower global warming potentials. Tradeoffs between global warming potential, flammability, and specific capacity will need to be made and these tradeoffs may result in the need for changes to equipment designs. Some lower global warming potential refrigerants are beginning to be introduced in many market segments. This article provides an overview of the next generation refrigerants available or under development and presents the state of understanding and development of these alternatives by their environmental, safety, and design tradeoffs.

Estimating the viscosity of pure refrigerants and their mixtures by free-volume theory

In this work, the free-volume theory (FVT) was extended to modeling the viscosities of 24 hydrofluorocarbon refrigerants, and applied to predict the viscosities for the mixtures of hydrofluorocarbon refrigerants. It is the first time to apply the FVT to the viscosities of ternary mixtures of hydrofluorocarbon refrigerants. Hydrofluoro-olefins (HFOs) are a new class of refrigerants, which are identified as promising refrigerants because they have low global warming potential, were studied in this paper. For the viscosity of pure refrigerants, the average absolute relative deviations between the FVT calculation and experiment are less than 1.5%. When calculating the viscosities of the mixtures of hydrofluorocarbon refrigerants, three mixing rules without more parameters were tested and compared, the average absolute relative deviations between the FVT coupled with the best mixing rule and experiment are less than 6.5%.

Thermodynamic Optimization of Solar-Driven Refrigerators

This paper describes the thermodynamic optimization of a class of refrigerators without work input, which are driven by heat transfer from a solar collector. The model consists of a finite-size solar collector with heat loss to the ambient, and a refrigerator with three finite-size heat exchangers, namely, the evaporator between refrigeration load and refrigerant, the condenser between the refrigerant and the ambient, and the heat exchanger between the solar collector and the refrigerant. The total thermal conductance of the three heat exchangers is fixed. The solar collector heat loss to the ambient is proportional to the collector-ambient temperature difference. The first part of the paper reports the operating conditions for maximum refrigeration effect, specifically, the optimal collector temperature, and the optimal way of allocating the thermal conductance inventory to the three heat exchangers. For example, the optimal condenser conductance is equal to half of the total thermal conductance, and is independent of other operating parameters. The second part of the paper examines the changes in the optimal design when the price of the refrigeration load (pL) is different (higher) than the price of the heat input provided by the collector (pH). The optimal collector temperature and the optimal three-way allocation of the thermal conductance inventory are reported as functions of the price ratio pH/pL.