scholarly journals Design Evaluation for a Finned-Tube CO2 Gas Cooler in Residential Applications

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2428 ◽  
Author(s):  
Charalampos Alexopoulos ◽  
Osama Aljolani ◽  
Florian Heberle ◽  
Tryfon C. Roumpedakis ◽  
Dieter Brüggemann ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Air Conditioning ◽  
Design Procedure ◽  
Finned Tube ◽  
Co2 Gas ◽  
Ambient Temperatures ◽  
Overall Heat Transfer Coefficient

Towards the introduction of environmentally friendlier refrigerants, CO2 cycles have gained significant attention in cooling and air conditioning systems in recent years. In this context, a design procedure for an air finned-tube CO2 gas cooler is developed. The analysis aims to evaluate the gas cooler design incorporated into a CO2 air conditioning system for residential applications. Therefore, a simulation model of the gas cooler is developed and validated experimentally by comparing its overall heat transfer coefficient. Based on the model, the evaluation of different numbers of rows, lengths, and diameters of tubes, as well as different ambient temperatures, are conducted, identifying the most suitable design in terms of pressure losses and required heat exchange area for selected operational conditions. The comparison between the model and the experimental results showed a satisfactory convergence for fan frequencies from 50 to 80 Hz. The absolute average deviations of the overall heat transfer coefficient for fan frequencies from 60 to 80 Hz were approximately 10%. With respect to the gas cooler design, a compromise between the bundle area and the refrigerant pressure drop was necessary, resulting in a 2.11 m2 bundle area and 0.23 bar refrigerant pressure drop. In addition, the analysis of the gas cooler’s performance in different ambient temperatures showed that the defined heat exchanger operates properly, compared to other potential gas cooler designs.

scholarly journals Experimental and CFD investigation of overall heat transfer coefficient of finned tube CO2 gas coolers

2019 ◽  
Vol 161 ◽  
pp. 300-308 ◽  
Author(s):  
IDewa M.C. Santosa ◽  
Konstantinos M. Tsamos ◽  
Baboo L. Gowreesunker ◽  
Savvas A. Tassou
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Finned Tube ◽  
Co2 Gas ◽  
Overall Heat Transfer Coefficient

Heat Transfer and Pressure Drop Analysis of Chilled Water and Ice Slurry in a Plate Heat Exchanger

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Rajinder Singh ◽  
Surendra Singh Kachhwaha
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Plate Heat Exchanger ◽  
Ice Slurry ◽  
Plate Heat ◽  
Overall Heat Transfer Coefficient ◽  
Chilled Water

The present study reports the experimental validation of thermohydraulic modeling for prediction of pressure drop and heat transfer coefficient. Experiments were performed on plate heat exchanger using chilled water and ice slurry as secondary fluids. Propylene glycol (PG) and mono-ethylene glycol (MEG) are used as depressants (10%, 20%, 30%, and 40% concentration) in ice slurry formation. The results show that thermohydraulic modeling predicts the pressure drop and overall heat transfer coefficient for water to water and water to ice slurry within the discrepancy limit of ±15%.

scholarly journals Cooling of High Heat Flux Flat Surface with Nanofluid Assisted Convective Loop: Experimental Assessment

2017 ◽  
Vol 64 (4) ◽  
pp. 519-531 ◽  
Author(s):  
Amir Arya ◽  
Saeed Shahmiry ◽  
Vahid Nikkhah ◽  
Mohamad Mohsen Sarafraz
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
High Heat ◽  
High Heat Flux ◽  
Overall Heat Transfer Coefficient ◽  
Cooling Loop ◽  
The Heat Transfer Coefficient

Abstract Experimental investigation was conducted on the thermal performance and pressure drop of a convective cooling loop working with ZnO aqueous nanofluids. The loop was used to cool a flat heater connected to an AC autotransformer. Influence of different operating parameters, such as fluid flow rate and mass concentration of nanofluid on surface temperature of heater, pressure drop, friction factor and overall heat transfer coefficient was investigated and briefly discussed. Results of this study showed that, despite a penalty for pressure drop, ZnO/water nanofluid was a promising coolant for cooling the micro-electronic devices and chipsets. It was also found that there is an optimum for concentration of nanofluid so that the heat transfer coefficient is maximum, which was wt. % = 0.3 for ZnO/water used in this research. In addition, presence of nanoparticles enhanced the friction factor and pressure drop as well; however, it is not very significant in comparison with those of registered for the base fluid.

scholarly journals Numerical Analysis of Heat Transfer and Pressure Drop in Helically Micro-Finned Tubes

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 754
Author(s):  
Muhammad Ammar Ali ◽  
Muhammad Sajid ◽  
Emad Uddin ◽  
Niaz Bahadur ◽  
Zaib Ali
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Thermal Performance ◽  
Finned Tube ◽  
Smooth Tube ◽  
Working Fluid ◽  
Finned Tubes

In this study, the pressure drop and heat transfer characteristics of smooth tube and internal helically micro-finned tubes with two different fin-to-fin height ratios i.e., equal fin height and alternating fin height, are computationally analysed. The tube with alternating fin height is analysed for proof of concept of pressure drop reduction. A single phase steady turbulent flow model is used with a Reynolds number ranging from 12,000 to 54,000. Water is used as working fluid with inlet temperature of 55 °C and constant wall temperature of 20 °C is applied. Friction factor, heat transfer coefficient, Nusselt number, and Thermal Performance Index are evaluated and analysed. The numerical results are validated by comparison with the experimental and numerical data from literature. The results showed that the thermal performance is enhanced due to helically finned tube for a range of Reynolds numbers, but at the expense of increased pressure drop as compared to a smooth tube. The helically finned tube with alternating fin heights showed a 5% decrease in friction factor and <1% decrease in heat transfer coefficient when compared with the equal fin heights tube, making it a suitable choice for heat transfer applications.

Performance of Dehumidifying Heat Exchangers With and Without Wetting Coatings

1999 ◽  
Vol 121 (4) ◽  
pp. 1018-1026 ◽  
Author(s):  
K. Hong ◽  
R. L. Webb
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Heat Exchangers ◽  
Finned Tube ◽  
Fin Efficiency ◽  
Dry Heat ◽  
Reduction Methods ◽  
Wet Surface

Limited previous work has shown that use of special hydrophilic coatings will provide lower air pressure drop in finned tube heat exchangers operated under dehumidifying conditions. However, no detailed work has been reported on the effect of different coating types, or different fin surface geometries on the wet pressure drop. In this study, wind tunnel tests were performed on three different fin geometries (wavy, lanced, and louver) under wet and dry conditions. All dehumidification tests were done for fully wet surface conditions. For each geometry, the tests were performed on uncoated and coated heat exchangers. For all three fin geometries, the wet-to-dry pressure drop ratio was 1.2 at 2.5 m/s frontal air velocity. The coatings have no influence on the wet or dry heat transfer coefficient. However, the wet surface heat transfer coefficient was 10 to 30 percent less than the dry heat transfer coefficient, depending on the particular fin geometry. The effect of the fin press oil on wet pressure drop was also studied. If the oil contains a surfactant, good temporary wetting can be obtained on an uncoated surface; however, this effect is quickly degraded as the oil is washed from the surface during wet operation. This work also provides a critical assessment of data reduction methods for wet surface operation, including calculation of the fin efficiency.

scholarly journals Mini Channel Evaporator as MAC Device for Laptop Cooling System

2020 ◽  
Vol 8 (5) ◽  
pp. 2993-2998
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Air Conditioning ◽  
Cooling System ◽  
Laptop Computer ◽  
Air Conditioning System ◽  
Overall Heat Transfer Coefficient ◽  
Flow Through ◽  
Cooling Methods

Laptop computers are known for their compact features which lead to overheating problems. Along with its being compact, laptop computer developers are going for more advance components to be able to run advance computer programs making the laptop do much more which also adds more to the overheating problems of the laptop. Overheated laptops will lead to slower laptop performances, laptop failures and even damaging its components. This problem leads to the development of laptop cooling methods, from fans and blowers and other cooling methods. This study aims to develop a cooling system which involves an air-conditioning system, a Mini Air Conditioning System (MAC System). The key to this study is the fabrication of three(3) mini channel evaporators which has different inner hydraulic diameters but of the same surface area with an overall size and which is smaller than a laptop battery pack. The evaporator for this study was made from a copper block that was fabricated to produce fins and a groove for the refrigerant to flow through the evaporator. The inner hydraulic diameters for the refrigerant to flow through are, 1mm, 2mm, and 3mm. The overall heat transfer coefficient would be determined for each evaporator size. The study showed that the most effective evaporator for cooling the laptop was that of the 3mm evaporator and that using the MAC system is an effective way of cooling a laptop computer. It lowered the temperature of the laptop by 10.65 K versus the setup with no cooler at all and 8.01 K with the setup with a plain cooler. The study also showed that the 3mm evaporator has the highest overall heat transfer coefficient with 73.129W/m2K with a mass flow rate of 0.039 kg/s.

scholarly journals Investigation of Effect of Aluminium Oxide Nanoparticles on the Thermal Properties of Water-Based Fluids in a Double Tube Heat Exchanger

2021 ◽  
Vol 12 (2) ◽  
pp. 2618-2628
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Fluid Flow ◽  
Thermal Properties ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Base Fluid ◽  
Outer Tube ◽  
Overall Heat Transfer Coefficient

The thermal behavior of aluminium oxide-water nanofluid in a double pipe carbon steel heat exchanger was investigated in the present study. The overall heat transfer coefficient, Nusselt, and heat transfer coefficient of nanofluid were compared with the base fluid. The volume fraction of the nanoparticles was 1%. By adding nanoparticles to the fluid, the thermal properties of the base fluid improved significantly. The hot and cold fluid flow was considered counter-current, and the nanofluid was pumped into the inner tube and once into the outer tube, and the flow rate of each fluid was 0.05 kg/s. The convective heat transfer and the overall heat transfer coefficient enhanced 94% and 253% for the hot fluid flow in the outer tube and 308 % and 144% for the hot fluid flow in the inner tube, respectively. The pressure drop calculations also showed that the pressure drop would not change significantly when using nanofluid.

scholarly journals FORCED CONVECTION HEAT TRANSFER PERFORMANCE OF AN INTERNALLY FINNED TUBE

1970 ◽  
Vol 40 (1) ◽  
pp. 54-62 ◽  
Author(s):  
Asharful Islam ◽  
A. K. Mozumder
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Heat Transfer Performance ◽  
Finned Tube ◽  
Transfer Performance

Heat transfer performance of T-section internal fins in a circular tube has been experimentally investigated. The T-finned tube was heated by electricity and was cooled by fully developed turbulent air. Inside wall temperatures and pressure drop along the axial distance of the test section at steady state condition were measured for different flows having Reynolds number ranging from 2x104 to 5x104 for both smooth and finned tubes. From the measured data, heat transfer coefficient, Nusselt number and friction factor were calculated. From the measured and calculated values, heat transfer characteristics and fluid flow characteristics of the finned tube are explained; the performance of the finned tube is also evaluated. For finned tube, friction factor on an average was 5 times higher and heat transfer coefficient was 2 times higher than those for smooth tube for similar flow conditions. The finned tube, however, produces significant heat transfer enhancement. Key Words: Heat Transfer, Internal Fin, Reynolds Number, Nusselt Number, Pressure Drop. doi: 10.3329/jme.v40i1.3473 Journal of Mechanical Engineering, Vol. ME40, No. 1, June 2009 54-62

Experimental Investigation of Thermal and Hydraulic Performance of V-Shape Corrugated Carbon Foam

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
W. Aboelsoud ◽  
W. Wu ◽  
L. C. Chow ◽  
B. A. Saarloos ◽  
D. P. Rini
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Carbon Foam ◽  
Heat Fluxes ◽  
Ambient Temperatures ◽  
Test Pieces ◽  
Air Cooled Heat Exchanger

In air-cooled heat exchangers, air-side thermal resistance is usually the largest compared to conduction and liquid-side thermal resistances. Thus, reducing the air-side thermal resistance can greatly improve overall cooling performance. The performance of an air-cooled heat exchanger is usually characterized by the rate of heat which can be transferred and the pumping power required to convect the heat away. This paper presents a method of utilizing V-shape corrugated carbon foam to improve thermal performance. The air-side heat transfer coefficient and the pressure drop across the foam have been investigated using different V-shape foam geometrical configurations obtained by varying its length and height. Based on design considerations and availability, the foam length has been chosen to be 25.4, 38.1, and 52.1 mm, while its height is 4.4, 6.8, and 11.7 mm, resulting in nine different test pieces of foam with different heights and lengths. A total number of 81 experiments were carried out with different air face velocities (0.7-9m/s) and heat fluxes at the heater surface (0.5-2W/cm2). The pressure drop across the V-shape corrugated carbon foam as well as inlet air, exit air, foam, and ambient temperatures were measured. Of the nine V-shape configurations, the foam with the shortest length and tallest height gives the best performance. The present results are also compared with the results of prior work using different carbon foam geometries. It is shown that V-shape corrugated carbon foam provides better heat transfer coefficient and the overall performance.

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