scholarly journals Experimental investigations with eco-friendly refrigerants using design of experiments technique-mathematical modeling and experimental validation

2014 ◽  
Vol 18 (suppl.2) ◽  
pp. 363-374 ◽  
Author(s):  
Kolandavel Mani ◽  
Vellappan Selladurai ◽  
Natarajan Murugan
Keyword(s):  
Mathematical Modeling ◽  
Design Of Experiments ◽  
Performance Prediction ◽  
Experimental Validation ◽  
Coefficient Of Performance ◽  
Experimental Investigations ◽  
Hydrocarbon Mixture ◽  
Refrigeration System ◽  
System Parameters ◽  
Vapour Compression

In this paper mathematical models were developed using design of experiments technique for the performance prediction of refrigeration system parameters such as refrigerating capacity, power consumption and coefficient of performance. The models developed were checked for their adequacy using F-test. The performances of vapour compression refrigeration system with different refrigerants R12, R134a and R290/R600a were compared. The R290/R600a mixture showed 10.7-23.6% higher coefficient of performance than that with R12 and R134a and it was found that the hydrocarbon mixture with 68% propane and 32% iso-butane could be used as a substitute for R12 and R134a.

scholarly journals Cop Enhancement of Vapour Compression Refrigeration System

2021 ◽  
pp. 1-6
Author(s):  
B Sairamakrishna ◽  
◽  
T Gopala Rao ◽  
N Rama Krishna ◽  
◽  
...  
Keyword(s):  
Tube Diameter ◽  
Coefficient Of Performance ◽  
Refrigeration System ◽  
Expansion Valve ◽  
Compressor Inlet ◽  
Work Input ◽  
Compressor Work ◽  
Vapour Compression ◽  
Design And Testing ◽  
Nozzle Inlet

This experimental investigation exemplifies the design and testing of diffuser at compressor inlet and nozzle at condenser outlet in vapour compression refrigeration system with the help of R134a refrigerant. The diffuser with divergence angle of 12°,14° and the nozzle with convergent angle 12°,14° are designed for same inlet and outlet diameters. Initially diffusers are tested at compressor inlet diffuser is used with inlet diameter equal to exit tube diameter of evaporator and outlet tube diameter is equal to suction tube diameter of the compressor. Diffuser helps to increases the pressure of the refrigerant before entering the compressor it will be helps to reduces the compression work and achieve higher performance of the vapour compression refrigeration system. Then nozzles are testing at condenser outlet, whereas nozzle inlet diameter equal to discharging tube diameter of condenser and outlet diameter equal to inlet diameter of expansion valve. Additional pressure drop in the nozzle helped to achieve higher performance of the vapour compression refrigeration system. The system is analyzes using the first and second laws of thermodynamics, to determine the refrigerating effect, the compressor work input, coefficient of performance (COP).

Experimental Analysis on Vapour Compression Refrigeration System Using Nanolubricant with HFC-134a Refrigerant

Nano Hybrids ◽  
2015 ◽  
Vol 9 ◽  
pp. 33-43 ◽  
Author(s):  
A. Manoj Babu ◽  
S. Nallusamy ◽  
K. Rajan
Keyword(s):  
Energy Consumption ◽  
System Performance ◽  
Mineral Oil ◽  
Coefficient Of Performance ◽  
Refrigeration System ◽  
Hfc 134A ◽  
Reduce Energy Consumption ◽  
And Performance ◽  
Vapour Compression ◽  
Better Than

This paper investigates the reliability and performance of a refrigeration system using nanolubricant with 1, 1, 1, 2-Tetrafluoroethane (HFC-134a) refrigerant. Mineral Oil (MO) is mixed with nanoparticles such as Titanium Dioxide (TiO2) and Aluminium Oxide (Al2O3). These mixtures were used as the lubricant instead of Polyolester (POE) oil in the HFC-134a refrigeration system as HFC-134a does not compatible with raw mineral oil. An investigation was done on compatibility of mineral oil and nanoparticles mixture at 0.1 and 0.2 grams / litre with HFC-134a refrigerant. To carry out this investigation, an experimental setup was designed and fabricated in the lab. The refrigeration system performance with the nanolubricant was investigated by using energy consumption test. The results indicate that HFC-134a and mineral oil with above mentioned nanoparticles works normally and safely in the refrigeration system. The refrigeration system performance was better than the HFC-134a and POE oil system. Thus nanolubricant (Mixture of Mineral Oil (MO) and nanoParticles) can be used in refrigeration system to considerably reduce energy consumption and better Coefficient of Performance (COP).

Environment Friendly Mixed Refrigerant to Replace R-134a in a VCR System with Exergy Analysis

2014 ◽  
Vol 984-985 ◽  
pp. 1174-1179
Author(s):  
N. Austin ◽  
P.M. Diaz ◽  
D.S. Manoj Abraham ◽  
N. Kanthavelkumaran
Keyword(s):  
Global Warming ◽  
Global Warming Potential ◽  
Ozone Depletion ◽  
Exergy Analysis ◽  
Coefficient Of Performance ◽  
Refrigeration System ◽  
Evaporator Temperature ◽  
Environment Friendly ◽  
A Charge ◽  
Vapour Compression

Study on environment friendly mixed refrigerant to replace R134a in vapour compression refrigeration (VCR) System. The mixed refrigerants investigated are propane (R290), butane (R600), isobutene (R600a) and R134a. Even though the ozone depletion potentials of R134a relative to CFC-11 are very low; the global warming potentials are extremely high and also expensive. For this reason, the production and use of R134a will be terminated in the near future. Hydrocarbons are free from ozone depletion potential and have negligible global warming potential. The results showed that, mixed refrigerant with charge of 80 g satisfy the required freezer air temperature when R134a with a charge of 110 g is used as refrigerant. The actual COP of refrigerator using mixed refrigerant was almost nearer that of the system using R134a as refrigerant. The coefficient of performance of the vapour compression refrigeration system using mixed refrigerant MR-3 [R134a/R290/ R600a/ R600 (20/35/40/5)] is having very close value with R134a and the Global warming potential of MR-3 is negligible when compared with R134a. Hence the mixed refrigerant MR-3 is chosen as an environmental friendly alternate refrigerant to R134a. The exergy analysis of the vapour compression refrigeration system using R134a and all the above mixtures are investigated. The effect of evaporator temperature on exergy efficiency and exergy destruction ratio of the system are experimentally studied. The exergy defect in the compressor, condenser, expansion device and evaporator are also obtained. Key words: R134a, Mixed refrigerant, Chlorofluorocarbons, Propane, Butane, Isobutene, REFPROP, COP, ODP, GWP, Exergy, VCR System.

scholarly journals COP enhancement of vapour compression refrigeration system using dedicated mechanical subcooling cycle

2020 ◽  
Vol 39 (3) ◽  
pp. 776-784
Author(s):  
T.S. Mogaji ◽  
A. Awolala ◽  
O.Z. Ayodeji ◽  
P.B. Mogaji ◽  
D.E. Philip
Keyword(s):  
System Performance ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Condensation Temperature ◽  
Refrigeration System ◽  
Wide Range ◽  
Cascade Refrigeration System ◽  
Cascade Refrigeration ◽  
Vapour Compression ◽  
Better Than

This study focused on development of an improved vapour compression refrigeration system (IVCR system). Dedicated mechanical subcooling cycle is employed in attaining the developed IVCR system. The system is composed of two cycles cascade refrigeration system working with R134a. It consists of a rectangular shape with total storage space of 0.582 m3, made of galvanized mild steel and internally insulated with 0.05 m polystyrene foam. Tests under a wide range operating temperature conditions were carried out on the developed IVCR system. Performance evaluation of the system was characterized in terms of cooling capacity and coefficient of performance (COP). Experimental results showed that the COP of the subcooled system improved better than that of the main system from 18.0% to about 33.5% over an evaporating temperature range of -10 to 30oC. It can be concluded that the use of dedicated sub cooling cycle in VCR system is more efficient and suitable for the betterment of thermal system performance. Keywords: Vapour compression Refrigeration system, Coefficient of performance, dedicated subcooled system, Condensation temperature, Evaporation temperature.

scholarly journals Performance Analysis of Vapour Compression Refrigeration System with Serpentine and Spiral Condensers by Using R600a

2019 ◽  
pp. 21-25
Author(s):  
P. Kesavulu ◽  
K. Prahlada Rao
Keyword(s):  
Coefficient Of Performance ◽  
Refrigeration System ◽  
Economic Output ◽  
Refrigeration Unit ◽  
Load Increase ◽  
Heating Load ◽  
Compressor Work ◽  
Cooling Loads ◽  
Vapour Compression ◽  
Ozone Depletion Potential

The present work is to analyse the performance of VCRS system with two condensers i.e., Serpentine and Spiral tube using Isobutane (R600a) refrigerant. These two condensers are kept in parallel with other components of refrigerating unit while construction. The performance of refrigeration system is checked for each condenser at various cooling loads. The performance of the condenser is measured for whole refrigeration unit in terms of C.O.P, compressor work, Efficiency of the system, Heat Rejection Ratio, and Heat Rejected from Condenser. The result will show that for both condensers for refrigerant R600a, coefficient of performance increases with increase in heating load, increase in refrigerating effect and decrease in compressor work. From the analysis of two condensers, coefficient of performance of refrigeration system using serpentine and spiral condenser VCRS is more compared to conventional VCRS. Also, R600a gives better cooling effect than tetrafluroethane (R134a). The substitution of R134a by R600a is useful in order to generate a good thermo-economic output, zero ODP (Ozone Depletion Potential) and very low GWP (Global Warming Potential).

scholarly journals Performance Prediction of Solar Adsorption Refrigeration System by Ann

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
V. Baiju ◽  
C. Muraleedharan
Keyword(s):  
Neural Network ◽  
Performance Prediction ◽  
Conjugate Gradient ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Performance Parameters ◽  
Refrigeration System ◽  
Back Propagation Algorithm ◽  
Adsorption Refrigeration ◽  
Discharge Temperature

This paper proposes a new approach for the performance analysis of a single-stage solar adsorption refrigeration system with activated carbon-R134a as working pair. Use of artificial neural network has been proposed to determine the performance parameters of the system, namely, coefficient of performance, specific cooling power, adsorbent bed (thermal compressor) discharge temperature, and solar cooling coefficient of performance. The ANN used in the performance prediction was made in MATLAB (version 7.8) environment using neural network tool box.In this study the temperature, pressure, and solar insolation are used in input layer. The back propagation algorithm with three different variants namely Scaled conjugate gradient, Pola-Ribiere conjugate gradient, and Levenberg-Marquardt (LM) and logistic sigmoid transfer function were used, so that the best approach could be found. After training, it was found that LM algorithm with 9 neurons is most suitable for modeling solar adsorption refrigeration system. The ANN predictions of performance parameters agree well with experimental values with R2 values close to 1 and maximum percentage of error less than 5%. The RMS and covariance values are also found to be within the acceptable limits.

SIMULATION OF A SIMPLE VAPOUR-COMPRESSION REFRIGERATION SYSTEM USING R134a

2016 ◽  
Vol 78 (9-2) ◽  
Author(s):  
Mohd Yusoff Senawi ◽  
Farah Wahidah Mahmod
Keyword(s):  
Steady State ◽  
Coefficient Of Performance ◽  
Refrigeration System ◽  
Input Coefficient ◽  
Work Input ◽  
Compressor Work ◽  
Computerized Simulation ◽  
Steady State Simulation ◽  
Vapour Compression ◽  
Isentropic Efficiency

A computerized simulation of a simple single-stage vapour-compression refrigeration system has been made. The steady-state simulation uses the accurate property correlations developed by Cleland for refrigerant R134a. The inputs to the program are: evaporator pressure, condenser pressure, superheating at evaporator outlet, subcooling at condenser outlet and compressor isentropic efficiency. The program outputs are: refrigerating effect, compressor work input, coefficient of performance (COP) and suction vapour flow rate per kW of refrigeration. An increase in the evaporator pressure from 150 to 250 kPa improves the COP by 40%. The COP is decreased by 35% when the condenser pressure is increased from 1000 to 1500 kPa. Increasing the superheat at the evaporator outlet from 0 to 160C improves the COP by 2.6%. An increase in subcooling at the condenser outlet from 0 to 160C increases the COP by 20%. The COP is improved by 150% when the compressor isentropic efficiency is increased from 0.4 to 1.

Optimum coefficient of performance and exergetic efficiency of a two-stage vapour compression refrigeration system

2003 ◽  
Vol 217 (9) ◽  
pp. 1027-1037 ◽  
Author(s):  
J S Tiedeman ◽  
S A Sherif
Keyword(s):  
Performance Optimization ◽  
Geometric Mean ◽  
Coefficient Of Performance ◽  
Second Law ◽  
Refrigeration System ◽  
Exergetic Efficiency ◽  
Two Stage ◽  
Optimization Study ◽  
The Common ◽  
Vapour Compression

This paper presents the results of an optimization study for a two-stage vapour compression refrigeration system based on the coefficient of performance (COP) and exergetic efficiency. Traditional studies have focused on the first-law performance, while those studies dealing with the second law have primarily been limited to performance analysis as opposed to performance optimization. The results of this study indicate that the use of the common approximation of the geometric mean to find the optimum interstage pressure can lead to significant errors in interstage pressure. However, an optimum COP or exergetic efficiency based on the same interstage pressure has relatively little error. This trend is valid as long as the isentropic compressor efficiencies are ‘reasonable’. Second-law optimization revealed that the optimum data curves themselves have a maxima for each set of conditions tested. This leads to the conclusion that for a given system there is an optimum set of conditions that lead to the lowest amount of exergy destruction for that system. This is shown to occur consistently for reasons that are, as yet, undetermined. Finally, polynomial equations have been fitted to the resultant optimum data for the interstage pressure, COP and exergetic efficiency. These equations allow for the reproduction of optimum points based on high-and low-pressure compressor efficiencies and condenser and evaporator pressures.

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