The heat exchangers tubes mineral type effect on the refrigeration system performance using different lengths of the capillary tube

2021 ◽  
pp. 095440622110022
Author(s):  
Thamer Khalif Salem ◽  
Saad Sami Farhan ◽  
Raaid Rashad Jassem Al Doury ◽  
Israa Sami Farhan
Keyword(s):  
Heat Exchangers ◽  
System Performance ◽  
Capillary Tube ◽  
Experimental Results ◽  
Tube Length ◽  
Working Fluid ◽  
Internal Diameter ◽  
Refrigeration System ◽  
Transfer Unit ◽  
Mineral Type

An experimental study is conducted to show the influence of the tubes material type of the heat exchanger on the refrigeration system performance. The system is operated by using R134a as a working fluid, 2 mm internal diameter, and different lengths of capillary tubes which were 120, 135, and 150 cm. The experimental results showed that when increasing the refrigerant mass flowrates led to reducing each of the performance coefficient COP, number of transfer unit NTU and evaporator effectiveness ε. However, the highest improvement had appeared for each parameter COP, NTU, and ε which were 21%, 113.38%, and 59.42% respectively at a capillary tube length of 120 cm and [Formula: see text] = 3.19 g/s compared to the length of capillary tube 150 cm. Besides, it was found an increase in [Formula: see text] with the incrementing in the capillary tube length from 120 cm to 150 cm. The biggest percentage of compression power was 23% at the capillary tube length of 150 cm compared to others at [Formula: see text] = 3.71 g/s. Finally, the experimental results of COP and [Formula: see text] were validated by comparing them with other publications.

THE EFFECT OF LIQUID SUCTION HEAT EXCHANGER SUB-COOLER ON PERFORMANCE OF A FREEZER USING R404A AS WORKING FLUID

2015 ◽  
Vol 76 (11) ◽  
Author(s):  
Muhammad Nuriyadi ◽  
Sumeru Sumeru ◽  
Henry Nasution
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Cooling Capacity ◽  
Experimental Results ◽  
Working Fluid ◽  
Liquid Line ◽  
Cabin Temperature

This study presents the effect of liquid-suction heat exchangers (LSHX) sub-cooler in a freezer. The LSHX sub-cooler is a method to increase the cooling capacity of the evaporator by lowering temperature at the condenser outlet. The decrease in temperature of the condenser outlet will cause a decrease in the quality refrigerant entering the evaporator. The lower the quality of the refrigerant entering the evaporator, the higher the cooling capacity produced by the evaporator. The LSHX sub-cooler utilizes a heat exchanger to transfer heat from the outlet of the condenser (liquid line) to the suction of the compressor. In the present study, three different LSHX sub-coolers in the freezer with cabin temperature settings of 0, -10 and -20oC were investigated. The results showed that the lowest and the highest of effectiveness of the heat exchanger were 0.28 and 0.58, respectively. The experimental results also showed that EER reduction is occurred at the cabin temperature setting of 0oC and -10oC, whereas the EER improvements were always occurred at the cabin temperature settings of -20oC.

Performance of Oil Separator According to the Depth of the Outlet Tube

2015 ◽  
Author(s):  
Seongil Jang ◽  
Joon Ahn ◽  
Si Hyung Lim
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Pressure Drop ◽  
Separation Efficiency ◽  
Lubricating Oil ◽  
Tube Length ◽  
Working Fluid ◽  
Energy Losses ◽  
Refrigeration System ◽  
Outlet Tube

Recent years have witnessed a growing concern over saving energy because of global warming issues and energy price hikes caused by increased oil prices. The need to improve energy efficiency to reduce energy consumption has been raised. Refrigeration systems are also expected to have their energy efficiency improved. A refrigeration system’s the compressor uses lubricating oil. Lubricating oil, along with refrigerant, circulates in a refrigeration system. During this process, the pressure drop increases, and the heat transfer coefficient decreases. Moreover, insufficient lubricant may incur a decrease in performance and damage to a compressor. Therefore, an oil separator is used to separate the lubricant and return it to the compressor. Since an oil separator causes an additional pressure drop, energy consumption should be decreased by increasing the oil separator’s separation efficiency and decreasing the pressure drop. The recent increase in development of large-scale buildings such as skyscrapers and large supermarkets has also increased the demand for large refrigeration machines. At the same time, refrigeration piping is becoming longer, and refrigerant must circulate up to the highest points. A high-pressure head and long piping configuration inevitably increase the quantity of lubricant left on the pipe wall, which in turn increases the loss of lubricants. The increased length and fall height for lubricants to circulate with refrigerant increase the related energy loss. In order to use a compressor in a high-head long-piping refrigeration system, the separation efficiency of the oil separator must be improved. Doing so will also reduce energy losses. Even with an improved separation efficiency, however, an increased pressure drop means additional energy losses. Thus, an oil separator with high separation efficiency and low pressure drop should be designed. So using the Numerical analysis, designed a new oil separator. A series of numerical simulation has been carried out to study peformance of a cyclone type oil separator, which is designed for the compressor of a refrigeration system. Working fluid is R22, which is a typical refrigerant, and mineral oil droplet is supplied. Depending on the outlet tube length, separation efficiency varies from 98.74 to 99.25%. Considering both of the separation efficiency, outlet tube length of the separator has been designed as 158 mm and oil separator length is 310mm.

Two Phase Heat Transfer of Ammonia in a Mini/Micro Channel

2010 ◽  
Author(s):  
M. Hamayun Maqbool ◽  
Bjo¨rn Palm ◽  
R. Khodabandeh ◽  
Rashid Ali
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Experimental Results ◽  
Working Fluid ◽  
Internal Diameter ◽  
Vapour Quality ◽  
The Heat Transfer Coefficient

Experiments have been performed to investigate heat transfer in a circular vertical mini channel made of stainless steel (AISI 316) with internal diameter of 1.70 mm and a uniformly heated length of 245 mm using ammonia as working fluid. The experiments are conducted for a heat flux range of 15 to 350 kW/m2 and mass flux range of 100 to 500 kg/m2s. The effects of heat flux, mass flux and vapour quality on the heat transfer coefficient are explored in detail. The experimental results show that the heat transfer coefficient increases with imposed wall heat flux while mass flux and vapour quality have no considerable effect. Experimental results are compared to predictive methods available in the literature for boiling heat transfer. The correlations of Cooper et al. [1] and Shah [3] are in good agreement with our experimental data.

scholarly journals Fabrication of Low Cost Refrigeration System by using LPG

2021 ◽  
pp. 282-286
Author(s):  
Utsav Shahare ◽  
Krishna Yadav ◽  
Viraj Dongre ◽  
Aryan Umre ◽  
Kalpesh Gajbhiye ◽  
...  
Keyword(s):  
High Pressure ◽  
Latent Heat ◽  
Capillary Tube ◽  
Low Cost ◽  
Phase Shifts ◽  
Phase Changes ◽  
Cooling Effect ◽  
Internal Diameter ◽  
Refrigeration System ◽  
Pressure Drops

We created and analysed a refrigerator that uses LPG as a refrigerant in this project. LPG is offered in high pressure cylinders. When this high-pressure LPG gas passes through a capillary tube with a tiny internal diameter, the pressure drops due to expansion, and the LPG phase shifts in an isoenthalpic process. The liquid refrigerant gains latent heat when its phase changes from liquid to gas, and the temperature drops. LPG can generate a cooling effect in this manner.

scholarly journals Effect of working fluids and internal diameters on thermal performance of vertical and horizontal closed-loop pulsating heat pipes with multiple heat sources

2016 ◽  
Vol 20 (1) ◽  
pp. 77-87 ◽  
Author(s):  
Niti Kammuang-Lue ◽  
Phrut Sakulchangsatjatai ◽  
Pradit Terdtoon
Keyword(s):  
Thermal Performance ◽  
Closed Loop ◽  
Capillary Tube ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Internal Diameter ◽  
Heat Sources ◽  
Pulsating Heat Pipe ◽  
Working Fluids ◽  
Fundamental Information

Some electrical applications have a number of heat sources. The closed-loop pulsating heat pipe (CLPHP) is applied to transfer heat from these devices. Since the CLPHP primarily transfers heat by means of the working fluid?s phase change in a capillary tube, the thermal performance of the CLPHP significantly depends on the working fluid type and the tube?s internal diameter. In order to provide the fundamental information for manufacturers of heat exchangers, this study on the effect of working fluids and internal diameters has been conducted. Three electrical plate heaters were installed on the CLPHP as the heat sources. The experiments were conducted by varying the working fluid to be R123, ethanol, and water, and the internal diameter to be 1.0 mm, 1.5 mm, and 2.0 mm. For each set of the same working fluid and internal diameter, the input heat fluxes of the heat sources were also made to vary within six different patterns. It can be concluded that when the latent heat of evaporation increases - in the case of vertical CLPHP - and when the dynamic viscosity of the liquid increases - in the case of horizontal CLPHP - the thermal performance decreases. Moreover, when the internal diameter increases, the thermal performance increases for both of vertical and horizontal CLPHPs.

Experimental Analysis of R134a/LPG as Replacement of R134a in a Vapor-Compression Refrigeration System

2017 ◽  
Vol 25 (02) ◽  
pp. 1750015 ◽  
Author(s):  
Jatinder Gill ◽  
Jagdev Singh
Keyword(s):  
Experimental Analysis ◽  
Capillary Tube ◽  
Energy Performance ◽  
Tube Length ◽  
Vapor Compression ◽  
Refrigeration System ◽  
Experimental Conditions ◽  
Discharge Temperature ◽  
Wide Range ◽  
Vapor Compression Refrigeration

This paper presents an experimental analysis of a vapor compression refrigeration system (VCRS) using the mixture of R134a and LPG with mass fractions of 28:72 as an alternative to R134a. In this work, we compare the energy performance of both refrigerants, R134a/LPG (28:72) and R134a, in a monitored vapor compression refrigeration system under a wide range of experimental conditions. So, the System with R134a/LPG (28:72) was tested by varying the capillary tube length and refrigerant charge under experimental conditions. Performance comparisons of both the systems are made taking refrigerant R134a as baseline, and the results show that the compressor power consumption, compressor discharge temperature and pull down time obtained with R134a/LPG (28:72) of 118[Formula: see text]g and capillary tube length of 5.1 m in vapor compression refrigeration system are about 4.4% 2.4% and 5.3%, respectively, lower than that obtained with R134a in the studied range. Also, when using R134a/LPG (28:72), the system shows values of refrigeration capacity and COP are about 10.6% and 15.2% respectively, higher than those obtained using R134a, In conclusion, the mixing refrigerant R134a/LPG proposed in this study seems to be an appropriate long-term candidate to replace R134a as a new generation refrigerant of VCRS, because of its well environmentally acceptable properties and its favorable refrigeration performances.

Experimental Investigation of Vapor Compression Refrigeration System Performance Using Nano-Refrigerant

2014 ◽  
Vol 2 (2) ◽  
pp. 12-27
Author(s):  
Ahmed J. Hamad
Keyword(s):  
Experimental Investigation ◽  
System Performance ◽  
Cuo Nanoparticles ◽  
Working Fluid ◽  
Vapor Compression ◽  
Refrigeration System ◽  
Test Rig ◽  
Vapor Compression Refrigeration ◽  
R 134A ◽  
Thermo Physical Properties

     Experimental investigation of vapor compression refrigeration system performance using Nano-refrigerant is presented in this work. Nano-refrigerant was prepared in current work by mixing 50 nanometers diameter of copper oxide CuO nanoparticles with Polyolester lubrication oil and added to the compressor of the refrigeration system to be mixed with pure refrigerant R-134a during its circulation through refrigeration system. Three concentrations (0.1%, 0.25%, and 0.4%) of CuO-R134 a Nano-refrigerant are used to study the performance of the refrigeration system test rig and to investigate the effect of using Nano-refrigerant as a working fluid compared with pure refrigerant R-134a. The results showed that, the increasing in concentration of CuO nanoparticles in the Nano-refrigerant will significantly enhance the performance of the refrigeration system, as adding nanoparticles will increase the thermal conductivity, heat transfer and improve the thermo-physical properties of Nano-refrigerant. Investigation of performance parameters for refrigeration system using Nano-refrigerant with 0.4% concentration compared with that for pure refrigerant R-134a shows that, Nano-refrigerant has reflect higher performance in range of 10% and 1.5% increase in COP and refrigeration effect respectively and 7% reduction in power consumption for refrigeration system. It can be concluded that, Nano-refrigerants can be efficiently and economically feasible to be used in the vapor compression refrigeration systems.

EXPERIMENTAL INVESTIGATION OF A REFRIGERATION SYSTEM WORKING UNDER TRANSIENT CONDITIONS

2014 ◽  
Vol 22 (03) ◽  
pp. 1450013 ◽  
Author(s):  
J. K. DABAS ◽  
SUDHIR KUMAR ◽  
A. K. DODEJA ◽  
K. S. KASANA
Keyword(s):  
Capillary Tube ◽  
Coefficient Of Performance ◽  
Tube Length ◽  
Design Parameters ◽  
Transient Operation ◽  
Refrigeration System ◽  
Transient Conditions ◽  
Cooling Period ◽  
Optimum Selection ◽  
The Impact

The impact of transient conditions along with varied capillary tube length and charge quantity over the performance of a simple refrigeration system under all time transient operations has been investigated in a specially designed experimental setup. A maximum drop of 75% in the coefficient of performance (COP) of the system was recorded by the end of the transient cooling period. The continuous deterioration in performance from start to end of the transient cooling job can be well minimized by the optimum selection of capillary tube length and charge quantity. This paper refers some of the existing methods to determine the appropriate length of the coiled capillary tube and charge quantity for a newly designed refrigeration machine working under steady state conditions and compares the experimental results of transient operation with these. Optimum charge quantity for transient operation in the present study is 3.5% to 5% less than that calculated by the existing analytical and numerical methods. The optimum length of coiled capillary tube for transient operation as found in this experimental study matches approximately with the length predicted by the existing dimensionless correlation on the basis of design parameters as estimated towards the end of the transient cooling period.

Aerodynamic and Thermal Measurements in a Standing Wave Thermoacoustic Refrigerator

2010 ◽  
Author(s):  
Gaelle Poignand ◽  
Emmanuel Jondeau ◽  
Philippe Blanc-Benon
Keyword(s):  
Heat Transfer ◽  
Standing Wave ◽  
Heat Exchangers ◽  
System Performance ◽  
Heat Fluxes ◽  
Acoustic Energy ◽  
Working Fluid ◽  
Cooling Power ◽  
Thermal Measurements ◽  
Thermoacoustic Refrigerator

Thermoacoustic refrigerators produce a cooling power from an acoustic energy. Over the last decades, these devices have been extensively studied since they are environment-friendly, robust and miniaturizable. Despite all these advantages, their commercialization is limited by their low efficiency. One reason for this limitation comes from the complex thermo-fluid process between the stack and the two heat exchangers which is still not sufficiently understood to allow for optimization. In particular, at high acoustic pressure level, vortex shedding can occur behind the stack as highlight by [Berson & al., Heat Mass Trans, 44, 10151023 (2008)]. The created vortex can affect heat transfer between the stack and the heat exchangers and thus, they can reduce the system performance. In this work, aerodynamic and thermal measurements are both conducted in a standing wave thermoacoustic refrigerator allowing investigation of vortex influence on the system performance. The proposed device consists on a resonator operated at frequency of 200 Hz, with hot and cold heat exchangers placed at the stack extremities. The working fluid is air at ambient temperature and atmospheric pressure. The aerodynamic field behind the stack is described using high-speed Particle Image Velocimetry. This technique allows the acoustic velocity field measurement at a frequency up to 3000 Hz. Thermal measurements consist on the acquisition of both the temperature evolution along the stack and the heat fluxes extracted at the cold heat exchanger. These measurements are performed by specific micro-sensors developed by MEMS technology. The combination of these two measurements should be helpful for the further understanding of the heat transfer between the stack and the heat exchangers.

Sign in / Sign up

Export Citation Format

Share Document