COP Of Refrigeration System Research Articles

Review on performance enhancement of solar absorption refrigeration system using various designs and phase change materials

Recent trend of increasing global warming throughout the world rising at very alarming rate. In leu of that, several efforts have been made by various researchers, among this solar refrigeration is one of the areas which required to be explored further. Conventional refrigerator consumes electricity which is mostly produced by power plant and most of the power plants in India running on coal, oil etc., which leads to rise of greenhouse gas production, that directly contribute to global warming. Several efforts have been made by researchers to enhance the performance of solar absorption refrigeration system. It has been found that the utilization of waste heat either from the marine ship engine or from the economizer can be used to run the ammonia water absorption refrigeration system. Few studies have been done on using phase change material to enhance the latent heat of fluid by various method which can be further used at night to supply it to generator of refrigeration system. The performance of vapour absorption refrigeration system has been enhanced significantly by using nanoparticles. Simulations studies gives interpretation of various design changes effect on the performance of solar refrigeration system and that can be used for further experimentation works. The effect of various design and operating parameters on the COP of refrigeration system have been reported by various researchers.

Effect of Addition of Different Mass Fractions of CuO Nano Particles in Compressor oil upon COP of the Refrigeration System

Nano fluids are produced by mixing particles of nano dimensions in the standard fluids. Thermal conductivities of the nanofluids are higher than that of the base fluids. These are the properties which makes nanofluids unique and superior to normal solid liquid suspensions. i) heat transfer between the particles and fluid is higher due to the high surface area of the particles ii) enhanced dispersion stability with pre-eminent Brownian motion iii) particle clogging is minimized iv) Power required for pumping is less as compared to the base fluid for proportionate heat transfer. In this project Cu0 nanoparticles of size 20nm-50nm has been used as Nano lubricant for performance study of Refrigeration test rig. CuO nanoparticles are mixed in POE oil (Compressor oil) to form the nanolubricant. The nanolubricant so formed is further stabilized by Ultrasonic agitation. Nano lubricants with specific mass fractions 0.30%, 0.70%, 1.05%, 1.4% are added in the compressor oil and the experimentation is carried out which shows significant improvement in the performance of refrigeration system. Compressor work is reduced and consequently COP of refrigeration system is improved.

Mechanism for improvement in refrigeration system performance by using nanorefrigerants and nanolubricants – A review

In order to improve the refrigeration system performance, researchers are introduced nanorefrigerants and nanolubricants in the recent development of HVAC system. However, the explanations of the nanoparticles contribution on the basis physical phenomena which affecting the vapor compression refrigeration system (VCRS) are limited in the literature. Hence, this paper presents a review on mechanism for improvement in VCRS performance by using nanorefrigerants and nanolubricants. The heat transfer augmentation, the refinement of refrigerant-oil mixture characteristic, and the tribology properties enhancement are among the major mechanisms that affect the VCRS performance. The performance parameters of VCRS such as compressor work and COP of refrigeration system using nanorefrigerants and nanolubricants have been discussed to relate between the mechanisms with overall system performance. The results showed that the utilization of nanorefrigerants and nanolubricants in the system was increased the heat transfer coefficients from 12 to 101% and the thermal conductivity enhancement for up to 4%. The solubility and miscibility of refrigerant-oil mixture with nanoparticles additives was enhanced for up to 12% although some reported that it was remained unchanged. The nanolubricants were behaved better tribology characteristics with 32% and 13% reduction of friction coefficient and wear rate, respectively. The effect of nanorefrigerants and nanolubricants on heat transfer, refrigerant-oil mixture and tribology had increased the overall performance of VCRS with 11% compressor work reduction and 24% of COP enhancement. Therefore, the nanorefrigerants and nanolubricants are expected to become the best candidate towards improving the efficiency of the VCRS.

Assessment of Alumina Nanofluid as a Coolant in Double Pipe Gas Cooler for Trans-critical CO 2 Refrigeration Cycle

Abstract In this study, the performance of an alumina nanofluid cooled double pipe gas cooler for trans-critical CO2 refrigeration cycle is theoretically compared to that of water cooled gas cooler. Equal pumping power comparison criterion is adopted besides conventional equal Reynolds number comparison base. Nanofluid is loaded with 0.5%, 1.5% and 2.5% of particle volume fraction under turbulent flow conditions. Drastic variation of thermal and transport properties of CO2 in the vicinity of pseudo critical temperature is taken care of by employing an appropriate discretization technique. Effect of gas cooler pressure, Reynolds number, pumping power and nanoparticle volume fraction on COP of refrigeration system, gas cooler overall conductance, effectiveness and its capacity has been studied. Results indicate that at equal Reynolds number comparison, performance for alumina nanofluid cooled system is better than that of water cooled system. On the other hand, at equal pumping power comparison basis, the performance of water cooled system is superior. Even at equal mass flow rate comparison criterion, the performance of nanofluid cooled system degrades with increase in particle volume fraction. This study is expected to help to assess the nanofluid as a coolant before expensive experimentation.