scholarly journals Case study of liquid suction heat exchanger in a mechanical refrigeration system using alternative refrigerants

2020 ◽  
Vol 9 (3) ◽  
pp. 644
Author(s):  
Raid Ahmed Mahmood
Keyword(s):  
Heat Exchanger ◽  
System Performance ◽  
Good Alternative ◽  
High Response ◽  
Coefficient Of Performance ◽  
Alternative Refrigerant ◽  
Refrigeration System ◽  
Alternative Refrigerants

This paper investigates the effect of adding a liquid-suction heat exchanger on the performance of a mechanical refrigeration system using alternative refrigerants. Engineering Equation Solver (EES) was used to simulate a mechanical refrigeration system in two configurations: modified system with liquid-suction heat exchanger and system without liquid-suction heat exchanger. The results revealed that the liquid-suction heat exchanger has a significant effect on the system performance as it influences the subcooling and superheating temperatures. The results also showed that the highest value of the coefficient of performance (COP) was achieved by the modified system with refrigerant type R134a, COP was about 7% and 12% higher than that of refrigerants R600a and R22 respectively. It also presented that R600a has high response to increase the refrigerant effect when the liquid-suction heat exchanger is used. R600a is good alternative refrigerant and it can be used in the mechanical refrigeration system, but its COP is lower than that of R134a.  

scholarly journals Analisis Numerik Simulasi Kinerja Sistem Tata Udara Unitary Menggunakan Liquid-Suction Heat Exchanger dengan Refrigeran Hidrokarbon

2018 ◽  
Vol 2 (2) ◽  
pp. 11
Author(s):  
Nuriyadi Muhammad
Keyword(s):  
Heat Exchanger ◽  
Air Conditioning ◽  
Environmental Issues ◽  
Coefficient Of Performance ◽  
Coolant Fluid ◽  
Alternative Refrigerant ◽  
Refrigeration System ◽  
Air Conditioning System ◽  
Liquid Line ◽  
Relative Capacity

<p><em>One of the environmental issues to be addressed, particularly in the field of refrigeration and air conditioning, is the destruction of the ozone layer and the effects of global warming due to the use of environmentally inefficient refrigerants. In the field of Refrigeration and Air Conditioning, refrigerant as a cooling medium, plays an important role, and until now there is still the use of refrigerant materials that are not environmentally friendly, generally synthetic refrigerant. One alternative refrigerant replacement against the synthetic refrigerant is hydrocarbon refrigerant (HC). On the other hand, several ways can improve the performance of refrigeration system by lowering the temperature of liquid line using liquid to suction heat exchanger. In this study, a numerical simulation was conducted to examine the effect of using liquid to suction heat exchanger on the performance of a unitary air-conditioning system using hydrocarbon refrigerant as a coolant fluid. The results are, liquid to suction heat exchanger increase refrigeration effect by raising heat exchanger effectivity, the highest increase is about 7%. But the use of LSHX also rises up the compression work by increasing heat exchanger effectivity by 19%. So the Coefficient of performance (COP) and relative capacity index decrease by 5%. Decreasing performance is higher in the unit that operates at higher temperatures.</em></p>

scholarly journals Performance Evaluation of a CO2 Refrigeration System Enhanced with a Dew Point Cooler

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1079 ◽  
Author(s):  
Martin Belusko ◽  
Raymond Liddle ◽  
Alemu Alemu ◽  
Edward Halawa ◽  
Frank Bruno
Keyword(s):  
Weather Conditions ◽  
Dew Point ◽  
Coefficient Of Performance ◽  
Experimental Program ◽  
Refrigeration System ◽  
Conventional System ◽  
Ambient Temperatures ◽  
Air Temperatures ◽  
Condenser Temperature

Dew point cooling (DPC) is a novel indirect evaporative cooling concept capable of delivering air temperatures approaching the dew point. Coupling this technology with CO2 refrigeration is well suited to minimising transcritical operation when the coefficient of performance (COP) is dramatically reduced in hot climates. A substantial experimental program was conducted to characterise this combination by testing a 20 kW CO2 refrigeration system subject to ambient temperatures above 40 °C. It was demonstrated that DPC operation not only avoided transcritical operation during such weather conditions, but also increased the COP by up to 140% compared to the conventional system. The combination of these technologies was successfully mathematically modelled, from which the optimum condenser inlet air temperature was identified for each condenser temperature. Using this optimum condition, it was possible to maximise the COP for a range of conditions applicable to the psychometric chart. An annual case study for Adelaide, Australia was conducted which demonstrated that optimally coupling DPC with CO2 refrigeration can reduce the annual energy consumption and peak demand by 16% and 47%, respectively, compared to a conventional CO2 booster system. Furthermore, the number of hours of transcritical operation was reduced from 3278 to 27.

Miniature Vapor Compression Refrigeration Systems for Active Cooling of High Performance Computers

2001 ◽  
Author(s):  
Ali Heydari ◽  
Kathy Russell
Keyword(s):  
Heat Exchanger ◽  
High Performance ◽  
Capillary Tube ◽  
New Technology ◽  
Mathematical Formulation ◽  
Coefficient Of Performance ◽  
Simulation Program ◽  
Vapor Compression ◽  
Refrigeration System ◽  
System Components

Abstract A small refrigeration system for cooling of computer system components is evaluated. A thermodynamic model describing the performance of the cycle along with a computer simulation program is developed to evaluate its performance. The refrigeration system makes use of a miniature reciprocating vapor compression compressor. Due to space limitations in some high performance computer servers, a miniature refrigeration system composed of a compressor, capillary tube, a compact condenser, and a cold-plate evaporator heat exchanger are used. Mathematical multi-zone formulation for modeling thermal-hydraulic performance of heat exchanger for the condenser and evaporator are presented. The throttling device is a capillary tube and there is presented a mathematical formulation for predicting refrigerant mass flow rate through the throttling device. A physically based efficiency formulation for simulating the performance of the miniature compressor is used. An efficient iterative numerical scheme with allowance for utilization of various refrigerants is developed to solve the governing system of equations. Using the simulation program, the effects of parameters such as the choice of working refrigerant, evaporating and condensing temperatures on system components and overall efficiency of system are studied. In addition, a RAS (reliability, availability and serviceability) discussion of the proposed CPU-cooling refrigeration solution is presented. The results of analysis show that the new technology not only overcomes many shortcomings of the traditional fan-cooled systems, but also has the capacity of increasing the cooling system’s coefficient of performance.

scholarly journals Heat Exchanger Network Synthesis Integrated with Compression–Absorption Cascade Refrigeration System

Processes ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 210 ◽  
Author(s):  
Xiaojing Sun ◽  
Linlin Liu ◽  
Yu Zhuang ◽  
Lei Zhang ◽  
Jian Du
Keyword(s):  
Heat Exchanger ◽  
Waste Heat ◽  
Coefficient Of Performance ◽  
Mixed Integer ◽  
Total Annual Cost ◽  
Network Synthesis ◽  
Refrigeration System ◽  
Operating Condition ◽  
Cascade Refrigeration System ◽  
Cascade Refrigeration

Compression–absorption cascade refrigeration system (CACRS) is the extension of absorption refrigeration system, which can be utilized to recover excess heat of heat exchanger networks (HENs) and compensate refrigeration demand. In this work, a stage-wise superstructure is presented to integrate the generation and evaporation processes of CACRS within HEN, where the generator is driven by hot process streams, and the evaporation processes provide cooling energy to HEN. Considering that the operating condition of CACRS has significant effect on the coefficient of performance (COP) of CACRS and so do the structure of HEN, CACRS and HEN are considered as a whole system in this study, where the operating condition and performance of CACRS and the structure of HEN are optimized simultaneously. The quantitative relationship between COP and operating variables of CACRS is determined by process simulation and data fitting. To accomplish the optimal design purpose, a mixed integer non-linear programming (MINLP) model is formulated according to the proposed superstructure, with the objective of minimizing total annual cost (TAC). At last, two case studies are presented to demonstrate that desired HEN can be achieved by applying the proposed method, and the results show that the integrated HEN-CACRS system is capable to utilize energy reasonably and reduce the total annualized cost by 38.6% and 37.9% respectively since it could recover waste heat from hot process stream to produce the cooling energy required by the system.

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).

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.

Comparison of Various Alternative Refrigerants for Vapour Compression Refrigeration Systems

2011 ◽  
Author(s):  
Ahmet Selim Dalkilic¸ ◽  
Somchai Wongwises
Keyword(s):  
Heat Exchanger ◽  
Single Stage ◽  
Refrigeration System ◽  
Performance Study ◽  
Alternative Refrigerants ◽  
Two Stage ◽  
Stage Process ◽  
Cascade Refrigeration System ◽  
Cascade Refrigeration ◽  
Vapour Compression

Single-stage vapour compression refrigeration system was compared with an actual vapour compression cycle, single-stage process with internal heat exchanger, and a two-stage process with economiser using the refrigerants of HCFC-22, CFC-502 and their alternatives such as HFC-134a, HFC-32, HFC-152a, HFC-404A, HFC-407C, HFC-507, HFC-410A. A theoretical performance study on a cascade refrigeration system was performed using two refrigeration cycles connected through the heat exchanger in the middle working as the evaporator for the high pressurized cycle and condenser for the low pressurized cycle. Other performance study was performed using a two-stage cascade refrigeration system having low and high pressure compressors connected through the mixing chamber in the middle. The condensation temperatures were between 30 and 50 °C, evaporation temperatures were between −50 °C and 5 °C and heat exchanger and economiser temperatures were kept as constant for the comparisons. Some of the alternative refrigerants’ coefficients of performance values are found to be higher than their base traditional pure refrigerants. The effects of the main parameters of performance analysis such as refrigerant type, degree of subcooling, and superheating on the performance coefficient, refrigerant charge rate and volumetric refrigeration capacity are investigated for various operating conditions as case studies.

scholarly journals Exergetic performance analysis of low GWP alternative refrigerants for R404A in a refrigeration system

2021 ◽  
Author(s):  
Mehmet Altinkaynak
Keyword(s):  
Cooling System ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Refrigeration System ◽  
Alternative Refrigerants ◽  
Condenser Temperature ◽  
Parametric Analyses ◽  
Low Global Warming Potential ◽  
Very High

Abstract According to the regulation of European Union laws in 2014, it was inevitable to switch to low global warming potential (GWP) fluids in the refrigeration systems where the R404A working fluid is currently used. The GWP of R404A is very high, and the potential for ozone depletion is zero. In this study, energetic and exergetic performance assessment of a theoretical refrigeration system was carried out for R404 refrigerant and its alternatives, comparatively. The analyses were made for R448A, R449A, R452A and R404A. The results of the analysis were presented separately in the tables and graphs. According to the results, the cooling system working with R448A exhibited the best performance with a coefficient of performance (COP) value of 2.467 within the alternatives of R404A followed by R449A and R452A, where the COP values were calculated as 2.419 and 2.313, respectively. In addition, the exergy efficiencies of the system were calculated as 20.62%, 20.22% and 19.33% for R448A, R449A and R452A, respectively. For the base calculations made for R404A, the COP of the system was estimated as 2.477, where the exergy efficiency was 20.71%. Under the same operating conditions, the total exergy destruction rates for R404A, R448A, R449A and R452A working fluids were found to be 3.201 kW, 3.217 kW, 3.298 kW and 3.488 kW, respectively. Furthermore, parametric analyses were carried out in order to investigate the effects of different system parameters such as evaporator and condenser temperature.

scholarly journals Refrigeration System Performance by Inserting Twisted Strip in Condenser Along With Liquid Suction Heat Exchanger

2019 ◽  
Vol 8 (6S4) ◽  
pp. 156-159 ◽  
Keyword(s):  
Heat Exchanger ◽  
System Performance ◽  
Cutting Edge ◽  
Vapor Compression ◽  
Refrigeration System ◽  
Condenser Tube ◽  
Evaporator Temperature ◽  
Vapor Compression Refrigeration ◽  
Tube Condenser

This paper gives preliminary aftereffects of VCR (Vapor Compression Refrigeration) go through setting twisted strip inside the condenser tube, using liquid suction warmth exchanger (lshe), and R134a as refrigerant in this cycle. examination executed on basic condenser tube with 3 different bended point strips verified in condenser tubes on the element of liquid suction heat exchanger for subcooling to remove suitable COP from cutting edge VCR machine. inside the proposed, lshe are taken through using each the procedures, strip focuses, α=a hundred,one hundred forty &one hundred eighty by methods for undeniable chamber and with subcooling. The proposed check has additionally made a through and through appraisal of COP, refrigeration influence, charge of impact and capability. in the communicated test; it's miles put that the drop in weight is 16% for the twisted strip tube condenser while in evaluation to customary condenser tube. other than it's in like manner seen that condenser with bowed strip implanted increments quick rot inside the temperature of evaporator than basic chamber. The effect and viability of misshaped strip verified cylinder condenser is unnecessary as strain drop falls in the condenser and decline of evaporator temperature

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