scholarly journals Performance Analysis and Optimization of an Ejector Refrigeration System Using Alternative Working Fluids under Critical and Subcritical Operation Modes

2021 ◽  
Author(s):  
Aggrey Mwesigye ◽  
Seth B. Dworkin
Keyword(s):  
Low Cost ◽  
Area Ratio ◽  
Environmentally Benign ◽  
Low Grade ◽  
Refrigeration System ◽  
Ejector System ◽  
Improved Model ◽  
Maintenance Requirements ◽  
Low Grade Heat ◽  
Modelling Approach

Ejector systems are receiving considerable attention due to their simplicity, lower maintenance requirements, use of low grade heat, longer lifespan and low cost. In this paper an improved model to predict the performance of an ejector refrigeration system under both the critical and subcritical modes of operation was developed and validated. The model predicts ejector performance more precisely compared to studies following the same modelling approach in the literature. Using the developed model, performances with environmentally benign refrigerants, including R1233zd(E), HFO1336mzz(Z), R1234ze(Z), R600, RE245fa2, and RE245fa2 as alternatives to R141b and R245fa were investigated. For ejector area ratios between 4.45 to 12.98, evaporator temperatures between 0oC and 16oC and condenser temperatures between 20 and 40oC, the optimal performance of the ejector system was determined. Results show that for each refrigerant, higher area ratios give higher coefficients of performance, but require higher generator temperatures for better critical condensing temperatures. R600 showed the best performance followed by R1234Ze(Z) and R1233Zd(E) for the entire range of parameters considered. Results further show that there is an optimum generator temperature at each area ratio that maximizes performance. The optimal generator temperature increases as the area ratio and the condensing temperature increase. An alternative and more convenient approach to optimize ejector performance has been suggested in this work.

scholarly journals Performance Analysis and Optimization of an Ejector Refrigeration System Using Alternative Working Fluids under Critical and Subcritical Operation Modes

2021 ◽  
Author(s):  
Aggrey Mwesigye ◽  
Seth B. Dworkin
Keyword(s):  
Low Cost ◽  
Area Ratio ◽  
Environmentally Benign ◽  
Low Grade ◽  
Refrigeration System ◽  
Ejector System ◽  
Improved Model ◽  
Maintenance Requirements ◽  
Low Grade Heat ◽  
Modelling Approach

Ejector systems are receiving considerable attention due to their simplicity, lower maintenance requirements, use of low grade heat, longer lifespan and low cost. In this paper an improved model to predict the performance of an ejector refrigeration system under both the critical and subcritical modes of operation was developed and validated. The model predicts ejector performance more precisely compared to studies following the same modelling approach in the literature. Using the developed model, performances with environmentally benign refrigerants, including R1233zd(E), HFO1336mzz(Z), R1234ze(Z), R600, RE245fa2, and RE245fa2 as alternatives to R141b and R245fa were investigated. For ejector area ratios between 4.45 to 12.98, evaporator temperatures between 0oC and 16oC and condenser temperatures between 20 and 40oC, the optimal performance of the ejector system was determined. Results show that for each refrigerant, higher area ratios give higher coefficients of performance, but require higher generator temperatures for better critical condensing temperatures. R600 showed the best performance followed by R1234Ze(Z) and R1233Zd(E) for the entire range of parameters considered. Results further show that there is an optimum generator temperature at each area ratio that maximizes performance. The optimal generator temperature increases as the area ratio and the condensing temperature increase. An alternative and more convenient approach to optimize ejector performance has been suggested in this work.

Investigations of thermal performance of ejection refrigeration system driven by low grade heat

2018 ◽  
Vol 130 ◽  
pp. 1121-1138 ◽  
Author(s):  
Jerzy Gagan ◽  
Kamil Śmierciew ◽  
Michał Łukaszuk ◽  
Dariusz Butrymowicz
Keyword(s):  
Thermal Performance ◽  
Low Grade ◽  
Refrigeration System ◽  
Low Grade Heat

Low Cost Solar Selective Chromate Conversion Coatings Applied to Stainless Steel Substrates

1980 ◽  
Vol 102 (3) ◽  
pp. 188-191 ◽  
Author(s):  
J. R. Culham ◽  
P. Niessen
Keyword(s):  
Stainless Steels ◽  
Low Cost ◽  
Low Grade ◽  
Conversion Coatings ◽  
Ferritic Stainless Steels ◽  
Good Thermal Stability ◽  
Chromate Conversion Coatings ◽  
Humidity Resistance ◽  
Low Grade Heat ◽  
Steel Substrates

Solar selective surfaces have been produced on austenitic and ferritic stainless steels using an acidic chromate bath at 75°C. These surfaces have been shown to have high humidity resistance and good thermal stability. The conversion coatings can be applied uniformly over large surfaces, even surfaces of nonplanar topography. Complete sets of plating parameters for different grades of stainless steels are presented which may be used for the implementation of this process for the production of low grade heat collecting systems.

Flexible low-grade energy utilization devices based on high-performance thermoelectric polyaniline/tellurium nanorod hybrid films

2016 ◽  
Vol 4 (9) ◽  
pp. 3554-3559 ◽  
Author(s):  
Y. Wang ◽  
S. M. Zhang ◽  
Y. Deng
Keyword(s):  
Energy Conversion ◽  
High Performance ◽  
Low Cost ◽  
Energy Utilization ◽  
Low Grade ◽  
Thermoelectric Generation ◽  
Hybrid Films ◽  
Direct Energy ◽  
Low Grade Heat ◽  
Polymer Thermoelectric

Solution based polymer thermoelectric generation technologies provide a low-cost and eco-friendly means of direct energy conversion from low-grade heat to electricity.

scholarly journals Monitoring System of a Heat Pump Installation for Heating a Rural House Using Low-grade Heat from a Surface Watercourse

2020 ◽  
Vol 9 (1) ◽  
pp. 11
Author(s):  
Valeriy Kharchenko ◽  
Arseniy Sychov ◽  
Pasquale Luigi De Angelis ◽  
Ugo Fiore
Keyword(s):  
Monitoring System ◽  
Heat Pump ◽  
Low Cost ◽  
Temperature Sensors ◽  
Low Grade ◽  
Analog To Digital ◽  
Frequency Output ◽  
Long Time ◽  
Computer Based ◽  
Low Grade Heat

Increasing the efficiency of heat pump systems primarily used for heat supply to buildings is an important topic. This is especially true for systems constructed according to non-standard schemes and which use low-grade heat from various sources that are rarely considered for these purposes. Such studies require special, often expensive, data acquisition systems. In this paper, a low-cost computer-based monitoring system is presented. The monitoring system incorporates solutions which are new or seldom used. It is shown that modern semiconductor thermistors can replace commonly used platinum temperature sensors and thermocouples. A proposal for processing frequency output signals from sensors through an analog-to-digital converter and a way to reduce the number of required input channels are described. The monitoring system allows optimization of various types of heat-pump-based installations. The system has been used for quite a long time to monitor the operation of the heat pump installation using low-grade heat from a surface watercourse. With its help, the feasibility of using the previously proposed submersible floating heat exchanger is justified and the optimal scheme for its placement in the watercourse is determined.

scholarly journals Investigations of prototype ejection refrigeration system driven by low grade heat

2018 ◽  
Vol 70 ◽  
pp. 03002 ◽  
Author(s):  
Dariusz Butrymowicz ◽  
Jerzy Gagan ◽  
Kamil Śmierciew ◽  
Michał Łukaszuk ◽  
Adam Dudar ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Heat Source ◽  
Air Conditioning ◽  
Thermal Capacity ◽  
Low Grade ◽  
Heat Sources ◽  
Refrigeration System ◽  
Gas Emission ◽  
Low Grade Heat ◽  
System Operating

One of possibilities of reduction of F-gas emission is application of low grade heat to drive the refrigeration systems as well as application of natural or low warming impact working fluids. The own experimental investigation of the ejection refrigeration system operating with refrigerant R-1234zeE are presented and discussed. The system is driven with low grade heat source of temperature below 70°C and thermal capacity approximately 90 kW. The experiments covered the effect of condensation, evaporation and generation temperatures on the capacity and thermal efficiency of the ejection refrigeration system operating for the air-conditioning purposes. Obtained results demonstrated that the proposed system may be thought as the promising heat driven refrigeration system with application of low grade motive heat sources.

Sign in / Sign up

Export Citation Format

Share Document