Experimental investigation of the heat transfer coefficient and pressure drop of R1234yf during flow condensation in helically coiled tubes

2020 ◽  
Vol 157 ◽  
pp. 106516 ◽  
Author(s):  
Sajjad Zakeralhoseini ◽  
Behrang Sajadi ◽  
Mohammad Ali Akhavan Behabadi ◽  
Soorena Azarhazin ◽  
Hamidreza Fazelnia
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Flow Condensation ◽  
The Heat Transfer Coefficient

scholarly journals Studies on the Heat Transfer Coefficient and Pressure Drop of Several Kinds of Plate Heat Exchanger

1968 ◽  
Vol 32 (11) ◽  
pp. 1127-1132,a1 ◽  
Author(s):  
Katsuto Okada ◽  
Minobu Ono ◽  
Toshio Tomimum ◽  
Hirotaka Konno ◽  
Shigemori Ohtani
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Plate Heat Exchanger ◽  
Plate Heat ◽  
The Heat Transfer Coefficient

scholarly journals Experimental and Simulation Study of Micro-Channel Backplane Heat Pipe Air Conditioning System in Data Center

2020 ◽  
Vol 10 (4) ◽  
pp. 1255
Author(s):  
Liping Zeng ◽  
Xing Liu ◽  
Quan Zhang ◽  
Jun Yi ◽  
Xiaohua Li ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Outlet Temperature ◽  
Transfer Performance ◽  
Micro Channel ◽  
Heat Transfer Capacity ◽  
The Heat Transfer Coefficient

This paper mainly studies the heat transfer performance of backplane micro-channel heat pipes by establishing a steady-state numerical model. Compared with the experimental data, the heat transfer characteristics under different structure parameters and operating parameters were studied, and the change of heat transfer coefficient inside the system, the air outlet temperature of the back plate and the influence of different environmental factors on the heat transfer performance of the system were analyzed. The results show that the overall error between simulation results and experimental data is less than 10%. In the range of the optimal filling rate (FR = 64.40%–73.60%), the outlet temperature at the lowest point and the highest point of the evaporation section is 22.46 °C and 19.60 °C, the temperature difference does not exceed 3 °C, and the distribution gradient in vertical height is small and the air outlet temperature is uniform. The heat transfer coefficient between the evaporator and the condenser is larger than the heat transfer coefficient under the conditions of low and high liquid charge rate. It increases gradually along the flow direction, and decreases gradually with the flow rate of the condenser. When the width of the flat tube of the evaporator increases from 20 mm to 28 mm, the internal pressure drop of the evaporator decreases by 45.83% and the heat exchange increases by 18.34%. When the number of evaporator slices increases from 16 to 24, the heat transfer increases first and then decreases, with an overall decrease of 2.86% and an increase of 87.67% in the internal pressure drop of the evaporator. The inclination angle of the corrugation changes from 30° to 60°, and the heat transfer capacity and pressure drop increase. After the inclination angle is greater than 60°, the heat transfer capacity and resistance decrease. The results are of great significance to system optimization design and engineering practical application.

Finned Metal Foam Heat Sinks for Electronics Cooling in Forced Convection

2002 ◽  
Vol 124 (3) ◽  
pp. 155-163 ◽  
Author(s):  
A. Bhattacharya ◽  
R. L. Mahajan
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Forced Convection ◽  
Metal Foam ◽  
Experimental Results ◽  
Heat Sinks ◽  
The Heat Transfer Coefficient

In this paper, we present recent experimental results on forced convective heat transfer in novel finned metal foam heat sinks. Experiments were conducted on aluminum foams of 90 percent porosity and pore size corresponding to 5 PPI (200 PPM) and 20 PPI (800 PPM) with one, two, four and six fins, where PPI (PPM) stands for pores per inch (pores per meter) and is a measure of the pore density of the porous medium. All of these heat sinks were fabricated in-house. The forced convection results show that heat transfer is significantly enhanced when fins are incorporated in metal foam. The heat transfer coefficient increases with increase in the number of fins until adding more fins retards heat transfer due to interference of thermal boundary layers. For the 20 PPI samples, this maximum was reached for four fins. For the 5 PPI heat sinks, the trends were found to be similar to those for the 20 PPI heat sinks. However, due to larger pore sizes, the pressure drop encountered is much lower at a particular air velocity. As a result, for a given pressure drop, the heat transfer coefficient is higher compared to the 20 PPI heat sink. For example, at a Δp of 105 Pa, the heat transfer coefficients were found to be 1169W/m2-K and 995W/m2-K for the 5 PPI and 20 PPI 4-finned heat sinks, respectively. The finned metal foam heat sinks outperform the longitudinal finned and normal metal foam heat sinks by a factor between 1.5 and 2, respectively. Finally, an analytical expression is formulated based on flow through an open channel and incorporating the effects of thermal dispersion and interfacial heat transfer between the solid and fluid phases of the porous medium. The agreement of the proposed relation with the experimental results is promising.

Microchannel Size Effects on Two-Phase Local Heat Transfer and Pressure Drop in Silicon Microchannel Heat Sinks With a Dielectric Fluid

2007 ◽  
Author(s):  
Tannaz Harirchian ◽  
Suresh V. Garimella
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Flow Boiling ◽  
Heat Sinks ◽  
Dielectric Fluid ◽  
Two Phase ◽  
Microchannel Heat Sinks ◽  
The Heat Transfer Coefficient

Two-phase heat transfer in microchannels can support very high heat fluxes for use in high-performance electronics-cooling applications. However, the effects of microchannel cross-sectional dimensions on the heat transfer coefficient and pressure drop have not been investigated extensively. In the present work, experiments are conducted to investigate the local flow boiling heat transfer in microchannel heat sinks. The effect of channel size on the heat transfer coefficient and pressure drop is studied for mass fluxes ranging from 250 to 1600 kg/m2s. The test sections consist of parallel microchannels with nominal widths of 100, 250, 400, 700, and 1000 μm, all with a depth of 400 μm, cut into 12.7 mm × 12.7 mm silicon substrates. Twenty-five microheaters embedded in the substrate allow local control of the imposed heat flux, while twenty-five temperature microsensors integrated into the back of the substrates enable local measurements of temperature. The dielectric fluid Fluorinert FC-77 is used as the working fluid. The results of this study serve to quantify the effectiveness of microchannel heat transport while simultaneously assessing the pressure drop trade-offs.

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 ANALISIS KINERJA CONDENSER SHELL AND TUBE UNIT 2 DI PT. PLN (PERSERO) SEKTOR ASAM-ASAM KALIMANTAN SELATAN

JTAM ROTARY ◽  
2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Hairudin Hairudin ◽  
Aqli Mursadin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Heat Balance ◽  
Balance Sheet ◽  
Average Heat ◽  
Shell And Tube ◽  
Fouling Factor ◽  
The Heat Transfer Coefficient

Theecondenser is a type of heat exchanger that functions to condense fluid. On steam powermsystems. Thevmain function ofmthe condenser is to convert steam into liquid. The purpose of this study is to determine the value and influence of heat balance, heat transfer coefficient, pressure drop and condenser efficiency.Thewresults offthissstudy indicate that in 2018 thee average heat balance (Q) was obtained at 356,017,533.46 Kj / hour while in 2019 the results of the average heat balance (Q) were 640,293,647,066 Kj / hour, fouling factor was not affect the balance sheet. The average gross heat transfer coefficient (UD) in 2018 amounted to 204,274.25 Kj / hour.m2. C and the average net heat transfer coefficient (UC) was 206,378 Kj / hr.m2. ° C whereas in 2019 the average heat transfer coefficient is obtained by the average gross heat transfer coefficient (UD) of 366,544.07 Kj / jam.m2. ° C and the Clean heat transfer coefficient (UC) is 448,554 Kj / h.m2. ° C.Fouling factor is very influential onnthe heatwtransfer coefficient because the greater the fouling in the tube will result in the inhibition of theeheat transfer rate in the tube, so that the heat transfer coefficient decreases. The pressure drop in 2018 is still within the permissible limits, with an average of 504.28 bars and 2019 of 513.03 bars. The effectiveness of the condenser in 2018 is an average of 23.330 after maintenance has been obtained, the average effectiveness of the condenser in 2019 is 40.743

scholarly journals Thermal-Hydraulic Performance of Graphene Nanoribbon and Silicon Carbide Nanoparticles in the Multi-Louvered Radiator for Cooling Diesel Engine

2020 ◽  
Vol 7 (1) ◽  
pp. F22-F29 ◽  
Author(s):  
E. Nogueira
Keyword(s):  
Heat Transfer ◽  
Silicon Carbide ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Analytical Solution ◽  
Transfer Coefficient ◽  
Mass Flow ◽  
Volume Fraction ◽  
Graphene Nanoribbon ◽  
The Heat Transfer Coefficient

Analytical solution for application and comparison of Graphene Nanoribbon and Silicon Carbide for thermal and hydraulic performance in flat tube Multi-Louvered Finned Radiator is presented. The base fluid is composed of pure water and ethylene glycol at a 50% volume fraction. The results were obtained for Nusselt number, convection heat transfer coefficient and pressure drop, for airflow in the radiator core and nanofluids in flat tubes. The main thermal and hydraulic parameters used are the Reynolds number, the mass flow rate, the Colburn Factor, and Friction Factor. In some situations, under analysis, the volume fraction, for Graphene Nanoribbon and Silicon Carbide, were varied. The value of the heat transfer coefficient obtained for Graphene Nanoribbon, for the volume fraction equal 0.05, is higher than twice the amount received by Silicon Carbide. The flow is laminar, for whatever the fraction value by volume of the Graphene nanoparticles when the mass flow of the nanofluid is relatively low. For turbulent flow and relatively small fractions of nanoparticles, the heat transfer coefficient is significantly high for mass flow rates of Graphene Nanoribbon. The pressure drop, for the same volume fraction of nanoparticles, is slightly higher than the pressure drop associated with Silicon Carbide. These high values for the heat transfer coefficient is a favorable result and of great practical importance, since lower values for the fraction in volume can reduce the costs of the compact heat exchanger (radiator). Keywords: analytical solution, nanofluid, compact exchanger, automotive radiator.

scholarly journals Energetic and Exergetic Assessment of Spiral Heat Exchanger Using Mineral and Oxide Mineral Oil Nanofluid

2021 ◽  
Vol 39 (2) ◽  
pp. 531-540
Author(s):  
Khalid Faisal Sultan ◽  
Mohammed Hassan Jabal ◽  
Ameer Abed Jaddoa
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Base Fluid ◽  
Exergy Efficiency ◽  
Exergy Destruction ◽  
Coiled Tube ◽  
Helically Coiled Tube ◽  
The Heat Transfer Coefficient

This paper presents an experimental analysis on the heat transfer and pressure drop enhancement of oil nanofluid flow. In this analysis, the first method has used the helically coiled tube and shell, the oil nanofluids were employed instead of the base fluid (oil) in the second process. the two techniques were used to improve the heat transfer and pressure drop. Nanofluid oil concentrations utilized within range from 1 to 5 percent vol. This paper applied two forms of nanoparticles: copper (Cu (20 nm)) and zirconium oxide (ZrO2 (40 nm)) and base fluid (oil). The influence on the heat transfer coefficient for different factors such as the flow number of Reynolds, the temperature of the nanofluid oil, the concentration and shape of the nanoparticle, and the pressure gradient of the flow have examined. The results indicated that the value of a 40.35 percent in the heat transfer coefficient for Cu + oil and 28.42 percent for ZrO2 + oil increased compared with the base fluid (oil) at 5 percent vol concentration. Using oil nanofluids (Cu, ZrO2 – oil) instead of the base fluid (oil) led to increasing in the heat transfer coefficient and decreasing the pressure. In addition, the result showed that the heat transfer efficiency has enhanced using the helically coiled tube and shell, as well as increasing in the pressure drop was due to the curvature of the tube. Baes on the relationship between viscosity and shear intensity, the oil nanofluid behaviors were similar to the standard Newtonian fluids. Moreover, the related flow and heat transfer methods are used to present the output index. The exergy inflow, exergy destruction and exergy efficiency of oil nanofluid (Cu +oil) were greater than the oil nanofluid (ZrO2 +oil) and oil. The exergy inflow, exergy destruction, and exergy efficiency for the two type of oil nanofluid increased with increasing of nanoparticles concentration.

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