The interest in application of secondary refiigerant systems in supermarket refrigeration is increasing. Reduced refrigerant losses i and the chance for lower installation and operation costs is promoting this development. There are also !options to use natural refrigerants, more efficient refrigerants and gas or waste heat driven absorption proc;esses. First installations of secondary refriger...

A New-PVE lubricant was developed for use with R32 refrigerant. R32 has been proposed as an alternative refrigerant for R410A refrigerant, to reduce global warming. In this report, we evaluated the relationship between the New-PVE lubricant and R32 and R410A refrigerants. The evaluation items were physical properties (miscibility, solubility, mixture viscosity and volumetric resistivity) and th...

Experimental investigation was done to find the role of capillary tube length and amount of refrigerant charge on the overall heat transfer coefficient in condenser and evaporator and actual COP of a simple vapour compression refrigeration system. It was concluded that increasing of the refrigerant charge in the system largely enhances the overall heat transfer coefficient in the evaporator by ...

Optimization of the refrigerant circuitry can improve a heat exchanger’s performance. Design engineers currently choose the refrigerant circuitry according to their experience and heat exchanger simulations. However, the design of an optimized refrigerant circuitry is difficult. The number of refrigerant circuitry candidates is enormous. Therefore, exhaustive search algorithms cannot be used an...

An experimental investigation was implemented to determine the capacity degradation due to non-uniform refrigerant and air flow distributions, and to assess the potential to recover the lost capacity via controlling refrigerant distribution between individual refrigerant circuits. The tests were performed on a three-circuit, threedepth-row, finned-tube evaporator. Refrigerant inlet quality, exi...

The use of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) has been widely restricted. They have been replaced with hydrofluorocarbons (HFCs) in order to protect the ozone layer. However, the leakage of refrigerant into the air from active or end-of-life air conditioners is a serious environmental issue owing to the high global warming potential (GWP) of HFCs. Therefore, replaci...

Automotive fixed orifice tube (FOT) systems are especially prone to cycling losses due to their clutch cycling operation. Therefore, it is important to better understand the dynamics of the refrigerant and oil migration during transient events such as cycling and start-up . To measure the refrigerant mass and oil distribution of an automotive R134a FOT breadboard system, two ball valves around ...

The primary goal of work described in this paper is to evaluate and enhance a virtual refrigerant charge sensor, developed in a previous study. The virtual refrigerant charge sensor algorithm employs low-cost and non-invasive measurements (i.e. surface mounted temperature measurements) to estimate refrigerant charge level for packaged air conditioning systems. It can be embedded within a portab...

Oil return from the evaporator to the compressor suction port is an important requirement. It is affected by the refrigerant/lubricant properties, gas velocities and piping geometry. The refrigerant R -134a has successfully replaced R-12 in household refrigerators and freezers. This paper describes a test method to estimate the mean oil film thickness and to observe the flow pattern in vertical...

This paper presents how the refrigerant dissolved in oil affects on Journal bearings reliability. The bearing model test is performed using the hermetic test apparatus. The oil film pressure is measured under several types of bearing grooves, L/D ratios and mixing ratios of refrigerant to oil. As a result, the means by which the refrigerant dissolved in oil causes damage to journal bearings is ...