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.

Energetic, Exergetic, Environmental, and Economic Assessment of a Cascade Refrigeration System Operating with Four Different Ecological Refrigerant Pairs

2021 ◽  
pp. 2150025
Author(s):  
Cleison Henrique de Paula ◽  
Willian Moreira Duarte ◽  
Thiago Torres Martins Rocha ◽  
Raphael Nunes de Oliveira ◽  
Antônio Augusto Torres Maia
Keyword(s):  
Coefficient Of Performance ◽  
Maintenance Cost ◽  
Temperature Cycle ◽  
Refrigeration System ◽  
Cascade System ◽  
Cost Rate ◽  
Total Plant ◽  
Cascade Refrigeration System ◽  
Cascade Refrigeration ◽  
System Operating

In this work, a cascade refrigeration system operating with four different ecological refrigerant pairs was modeled. This system uses R744 (Carbon dioxide) in the low-temperature cycle and operates with R290 (propane), R1234yf (2,3,3,3-tetrafluoropropene), R152a (1,1-difluorethane), and R717 (ammonia) in the high-temperature cycle. Energetic, exergetic, environmental, and economic performance of the cascade system was investigated to determine the most appropriate ecological refrigerant couple. The parameters used in each mentioned performance were COP (Coefficient of Performance), [Formula: see text] (Exergy Efficiency), TEWI (Total Equivalent Warming Impact), ECOP (Ecological coefficient of performance), and [Formula: see text] (Total plant cost rate), respectively. The results showed that the cascade refrigeration system operating with R744/R717 provided the best performance for the thermodynamic conditions analyzed, presenting a COP of 2.10, [Formula: see text] of 56.9%, [Formula: see text] of 24 334 USD/year, ECOP of 4.86, and TEWI of 25.67 tons of CO2. Finally, evaluating the total plant cost rate of this cascade system, it was noted that the capital and maintenance cost rate [Formula: see text] corresponds to 89.1% of the [Formula: see text] value, the operational cost rate [Formula: see text] corresponds to 10.27% of the [Formula: see text] value and the environmental cost rate [Formula: see text] corresponds to 0.63% of [Formula: see text].

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 Effect of subcooling and superheating on performance of a cascade refrigeration system with considering thermo- economic analysis and multi-objective optimization

2016 ◽  
Vol 5 (2) ◽  
pp. 42 ◽  
Author(s):  
Mohammad Mehdi Keshtkar
Keyword(s):  
Pareto Frontier ◽  
Total Annual Cost ◽  
Total System ◽  
Refrigeration System ◽  
Exergetic Efficiency ◽  
System Cost ◽  
Study Results ◽  
Cascade Refrigeration System ◽  
Cascade Refrigeration ◽  
Base Design

In present work, effect of degrees of subcooling and superheating based on thermoeconomic optimization is investigated in two stage-cascade refrigeration system (TS-CRS). At the first step, by using R717 and R744 as refrigerants, a thermoeconomic analysis is applied to TS-CRS. Based on results of the first section and using the genetic algorithm (GA) optimizer implemented in MATLAB, the optimum operative conditions of a specific TS-CRS is determined. Finally, based on the Pareto frontier obtained from the GA optimization, a decision-making strategy is then used to determine a final solution by TOPSIS method. Two single-objective optimization strategies (SOS), i.e. exergetic optimization and cost optimization, are applied on TS-CRS. The aim of the first strategy is to maximize the exergetic efficiency and the aim of the second strategy is minimizing the total annual cost of the system. The case study results show that, compared to the base design, the use of SOS for maximizing of exergetic efficiency can be increases the exergetic efficiency 94.5%. In addition, the use of the second SOS can decrease the total system cost by 11%. Using MOS compared to base design, exergetic efficiency and the total system cost can be increase by 99.1% and 28.6% respectively.

scholarly journals Experimental Analysis of the R744/R404A Cascade Refrigeration System with Internal Heat Exchanger. Part 1: Coefficient of Performance Characteristics

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 6003
Author(s):  
Min-Ju Jeon
Keyword(s):  
High Temperature ◽  
Experimental Studies ◽  
Internal Heat ◽  
Coefficient Of Performance ◽  
Temperature Cycle ◽  
Refrigeration System ◽  
Evaporation Temperature ◽  
Internal Heat Exchanger ◽  
Cascade Refrigeration System ◽  
Cascade Refrigeration

This study evaluates the performance of an R744/R404A cascade refrigeration system (CRS) with internal heat exchangers (IHE) in supermarkets. R744 is used as the refrigerant in a low-temperature cycle, and R404A is used as the refrigerant in a high-temperature cycle. In previous studies, there are many studies including theoretical performance analysis of the CRS. However, experimental studies on the CRS are lacking, and experimental research on the R744/R404A system with an IHE is scarce. Therefore, this study provides basic data for optimal refrigeration system design by experimentally evaluating the results of modifying various parameters. The operating parameters considered in this study include subcooling and superheating, condensing and evaporating temperature, cascade evaporation temperature, and IHE efficiency in the R744 low- and R404A high-temperature cycle. The main results are summarized as follows: (1) By applying the results of this study, energy efficiency is achieved by optimizing the overall coefficient of performance (COP) of the CRS, and the refrigerant charge of the R404A cycle is minimized and economic efficiency is also obtained, enabling operation and maintenance as an environment-friendly system. (2) When designing the CRS, finding the cascade evaporation temperature that has the optimum and maximum COP according to the refrigerant combination should be considered with the highest priority.

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