Charge optimisation of a solar milk chiller with direct current compressors

2020 ◽  
pp. 095440892096400
Author(s):  
Shaji Sidney ◽  
Rajendran Prabakaran ◽  
Mohan Lal Dhasan
Keyword(s):  
Direct Current ◽  
Coefficient Of Performance ◽  
Ice Formation ◽  
Exergy Destruction ◽  
Hfc 134A ◽  
Refrigerant Circuit ◽  
Maximum Coefficient ◽  
Photo Voltaic ◽  
Solar Powered ◽  
Optimum Charge

In view of promoting the utilization of solar photo-voltaic energy for milk chilling application a custom designed milk chiller with DC compressors was fabricated. Two different DC compressors were used operating with HFC-134a and HC-600a refrigerants to ascertain the performance of HFC and HC refrigerants when used in solar powered application. In view of optimizing the performance of both refrigerants, charge optimization was experimentally carried out for both refrigerant circuits. The optimum charge was obtained based on the maximum coefficient of performance and exergy efficiency. When comparing ice formation and coefficient of performance, the HC-600a refrigerant circuit was lower than that of HFC-134a circuit. It was also observed that the total exergy destruction experienced was maximum in the HFC-134a circuit than that of the HC-600a circuit. The magnitude of exergy destruction was found to be maximum in the compressor and then followed by the condenser, evaporator and finally the capillary for both refrigeration circuits. This study showed an efficient way for using the solar power for operating a milk chiller with DC compressors and with ice bank tank to avoid the dependency on batteries.

scholarly journals Performance Results of a Solar Adsorption Cooling and Heating Unit

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1630 ◽  
Author(s):  
Tryfon C. Roumpedakis ◽  
Salvatore Vasta ◽  
Alessio Sapienza ◽  
George Kallis ◽  
Sotirios Karellas ◽  
...  
Keyword(s):  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Solar Thermal Energy ◽  
Cooling Mode ◽  
Heating Unit ◽  
Adsorption Chiller ◽  
Maximum Coefficient ◽  
Solar Powered ◽  
Evacuated Tube Collectors ◽  
Performance Results

The high environmental impact of conventional methods of cooling and heating increased the need for renewable energy deployment for covering thermal loads. Toward that direction, the proposed system aims at offering an efficient solar powered alternative, coupling a zeolite–water adsorption chiller with a conventional vapor compression cycle. The system is designed to operate under intermittent heat supply of low-temperature solar thermal energy (<90 °C) provided by evacuated tube collectors. A prototype was developed and tested in cooling mode operation. The results from the testing of separate components showed that the adsorption chiller was operating efficiently, achieving a maximum coefficient of performance (COP) of 0.65. With respect to the combined performance of the system, evaluated on a typical week of summer in Athens, the maximum reported COP was approximately 0.575, mainly due to the lower driving temperatures with a range of 75 °C. The corresponding mean energy efficiency ratio (EER) obtained was 5.8.

scholarly journals Performance Results of a Solar Adsorption Cooling and Heating Unit

2020 ◽  
Author(s):  
Tryfonas Roumpedakis ◽  
Salvatore Vasta ◽  
Alessio Sapienza ◽  
George Kallis ◽  
Sotirios Karellas ◽  
...  
Keyword(s):  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Solar Thermal Energy ◽  
Cooling Mode ◽  
Heating Unit ◽  
Adsorption Chiller ◽  
Maximum Coefficient ◽  
Solar Powered ◽  
Evacuated Tube Collectors ◽  
Performance Results

The high environmental impact of conventional methods of cooling and heating has increased the need for renewable energy deployment for covering thermal loads. Towards that direction, the proposed system aims at offering an efficient solar powered alternative, coupling a zeolite-water adsorption chiller with a conventional vapor compression cycle. The system is designed to operate under intermittent heat supply of low-temperature solar thermal energy (&lt;90 &deg;C) provided by evacuated tube collectors. A prototype was developed and tested in cooling mode operation. The results of separate components testing showed that the adsorption chiller was operating efficiently, achieving a maximum coefficient of performance (COP) of 0.65. With respect to the combined performance of the system, evaluated on a typical week of summer in Athens, the maximum reported COP was approximately 0.575, mainly due to the lower driving temperatures at a range of 75 &deg;C. The corresponding mean energy efficiency ratio (EER) obtained was 5.8.

scholarly journals Efficiency Evaluation of the Ejector Cooling Cycle using a New Generation of HFO/HCFO Refrigerant as a R134a Replacement

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2136 ◽  
Author(s):  
Bartosz Gil ◽  
Jacek Kasperski
Keyword(s):  
High Efficiency ◽  
Coefficient Of Performance ◽  
Condensation Temperature ◽  
Evaporation And Condensation ◽  
Wide Range ◽  
Theoretical Investigations ◽  
Maximum Coefficient ◽  
C 30 ◽  
New Generation ◽  
And Control

Theoretical investigations of the ejector refrigeration system using hydrofluoroolefins (HFOs) and hydrochlorofluoroolefin (HCFO) refrigerants are presented and discussed. A comparative study for eight olefins and R134a as the reference fluid was made on the basis of a one-dimensional model. To facilitate and extend the possibility of comparing our results, three different levels of evaporation and condensation temperature were adopted. The generator temperature for each refrigerant was changed in the range from 60 °C to the critical temperature for a given substance. The performed analysis shown that hydrofluoroolefins obtain a high efficiency of the ejector system at low primary vapor temperatures. For the three analyzed sets of evaporation and condensation temperatures (te and tc equal to 0 °C/25 °C, 6 °C/30 °C, and 9 °C/40 °C) the maximum Coefficient of Performance (COP) was 0.35, 0.365, and 0.22, respectively. The best performance was received for HFO-1243zf and HFO-1234ze(E). However, they do not allow operation in a wide range of generator temperatures, and, therefore, it is necessary to correctly select and control the operating parameters of the ejector.

scholarly journals Thermal Performance Analysis of Low-GWP Refrigerants in Automotive Air-Conditioning System

2020 ◽  
Vol 2020 ◽  
pp. 1-14 ◽  
Author(s):  
Yousuf Alhendal ◽  
Abdalla Gomaa ◽  
Gamal Bedair ◽  
Abdulrahim Kalendar
Keyword(s):  
Air Conditioning ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Exergy Destruction ◽  
Air Conditioning System ◽  
Capacity Coefficient ◽  
Automotive Air Conditioning ◽  
Automotive Air Conditioning System ◽  
Compressor Power ◽  
Low Global Warming Potential

The energy and exergy of low-global warming potential (GWP) refrigerants were investigated experimentally and theoretically. Refrigerants with a modest GWP100 of  ≤ 150 can be sufficient for bringing down emissions which were concerned for the automotive air-conditioning system. Three types of low-GWP refrigerants, R152a, R1234yf, and R1234ze(E), were examined with particular reference to the current high-GWP of R134a. The effect of different evaporating and condensing temperatures in addition to compressor speed was considered. The purpose was to bring a clear view of the performance characteristics of possible environment friendly alternatives of R134a. The analysis was carried out with compressor power, cooling capacity, coefficient of performance, exergy destruction, and exergy efficiency. It was noted that the total exergy destruction of R1234yf was reduced by 15% compared to that of R134a. The refrigerant R1234ze(E) has the highest energetic and exergetic performance compared with the other investigated refrigerants.

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 Humidification–Dehumidification (HDH) Desalination System with Air-Cooling Condenser and Cellulose Evaporative Pad

Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 142 ◽  
Author(s):  
Li Xu ◽  
Yan-Ping Chen ◽  
Po-Hsien Wu ◽  
Bin-Juine Huang
Keyword(s):  
Waste Heat ◽  
Ambient Air ◽  
Structure Design ◽  
Coefficient Of Performance ◽  
Air Cooling ◽  
Cooling Medium ◽  
Maximum Coefficient ◽  
Output Ratio ◽  
Copper Material ◽  
Cooling Air

This paper presents a humidification–dehumidification (HDH) desalination system with an air-cooling condenser. Seawater in copper tubes is usually used in a condenser, but it has shown the drawbacks of pipe erosion, high cost of the copper material, etc. If air could be used as the cooling medium, it could not only avoid the above drawbacks but also allow much more flexible structure design of condensers, although the challenge is whether the air-cooing condenser can provide as much cooling capability as water cooling condensers. There is no previous work that uses air as cooling medium in a condenser of a HDH desalination system to the best of our knowledge. In this paper we designed a unique air-cooling condenser that was composed of closely packed hollow polycarbonate (PC) boards. The structure was designed to create large surface area of 13.5 m2 with the volume of only 0.1 m3. The 0.2 mm thin thickness of the material helped to reduce the thermal resistance between the warm humid air and cooling air. A fan was used to suck the ambient air in and out of the condenser as an open system to the environment. Results show that the air-cooling condenser could provide high cooling capability to produce fresh water efficiently. Meanwhile, cellulous pad material was used in the humidifier to enhance the evaporative process. A maximum productivity of 129 kg/day was achieved using the humidifier with a 0.0525 m3 cellulous pad with a water temperature of 49.5 °C. The maximum gained output ratio (GOR) was 0.53, and the maximum coefficient of performance (COP) was 20.7 for waste heat recovery. It was found that the system performance was compromised as the ambient temperature increased due to the increased temperature of cooling air; however, such an effect could be compensated by increasing the volume of the condenser.

Numerical Simulation of a Novel Solar-Powered Hybrid Energy System with Cooling and Heating

2011 ◽  
Vol 374-377 ◽  
pp. 470-474
Author(s):  
Hui Long Luo ◽  
Xiao Chen ◽  
Jin Hui Peng
Keyword(s):  
Solar Radiation ◽  
Energy System ◽  
Climatic Conditions ◽  
Coefficient Of Performance ◽  
Water Heater ◽  
Performance Simulation ◽  
Hybrid Energy System ◽  
Hybrid Energy ◽  
Solar Radiation Intensity ◽  
Solar Powered

A novel solar-powered hybrid energy system with cooling and heating is presented, which consists of an adsorption ice maker subsystem and water heater subsystem. It can be used as an ice maker and water heater hybrid system or a single water heater respectively according to incident solar radiation intensity. A numerical model is developed to predict the performances of the hybrid energy system. Performance simulation and analysis on the hybrid energy system have been made. Simulation results show that, under the climatic conditions of daily solar radiation being about 12-20MJ/m2, the hybrid energy system can be used as an ice maker and a water heater effectively, its daily solar cooling COP (coefficient of performance) is about 0.173 - 0.181, the daily heating coefficient of performance is about 0.294-0.327.

The maximum coefficient of performance (COP) of vortex tubes

2015 ◽  
Vol 93 (11) ◽  
pp. 1279-1282 ◽  
Author(s):  
Jeliazko G. Polihronov ◽  
Anthony G. Straatman
Keyword(s):  
First Principles ◽  
Vortex Tube ◽  
Temperature Drop ◽  
Coefficient Of Performance ◽  
Gas Compression ◽  
Maximum Coefficient ◽  
Vortex Tubes ◽  
Rotational Cooling

In a number of recent publications, it has been shown that the vortex tube effect occurs as a result of the extraction of work from a radial inflow of rotating gas. The delivered energy and its corresponding temperature drop have been derived from first principles. This work studies the cycle of rotational cooling by also considering the process of gas compression and arrives at the maximum theoretical value of the coefficient of performance (COP). For air, the maximum COP of the vortex tube effect is 2.5; it can reach over 15.0 for common refrigerants (e.g., R-218) and 20.0 or higher for other gases (e.g., n-heptane).

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