Paper 5: A Comparison of the Natural Convective Heat Transfer Performance of Three Fluids from a Horizontal Flat Surface near the Critical Point

1967 ◽  
Vol 182 (9) ◽  
pp. 27-35
Author(s):  
J. W. Bramall ◽  
T. C. Daniels
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Critical Region ◽  
Heat Transfer Performance ◽  
Heating Surface ◽  
Transfer Performance ◽  
Surface Geometry ◽  
Lack Of Information ◽  
Show Evidence

One of the main problems with heat transfer research in the critical region is the lack of accurate thermodynamic and transport property data. This lack of information makes the actual heat transfer performance very difficult to correlate, whilst the extreme property variations produce other effects, which are also dependent on the heating surface geometry. Three fluids, carbon dioxide, nitrous oxide, and chlorotrifluoromethane, were therefore tested with a view to establishing whether they had similar regions of heat transfer and whether any similarity with boiling existed. The results show that in the critical region the normal convective heat transfer is augmented by a process to give results which look very like the lower portion of the normal boiling curve. Finally the authors show evidence to support the theory that there are preferential areas of heat transfer in the supercritical region.

Enhanced Convective Heat Transfer in High Porosity Metal Foams

2014 ◽  
Author(s):  
L. W. Jin ◽  
C. F. Ma ◽  
M. Zhao ◽  
X. Z. Meng ◽  
W. B. Kang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Convective Heat Transfer ◽  
Forced Convection ◽  
Convective Heat ◽  
Heat Transfer Performance ◽  
Heating Surface ◽  
Metal Foams ◽  
High Porosity ◽  
Transfer Performance

Due to the characteristics of large surface area-to-volume ratio and inter-connected ligament structure, open-cell metal foams are promising materials for enhancing heat transfer in forced convection and have been researched for thermal applications in thermal management systems, air-cooled condensers and compact heat sinks for power electronics. However, the tortuous complex flow path inside metal foams leads to relatively higher pressure drop, which requires larger system pumping power. Hence, it is important to study the heat transfer performance of metal foam compared to its flow resistance characteristics. Detailed experimental study of forced convection subjected to constant heat flux in metal foams is conducted in the present paper. The objective of the investigation is to compare the heat transfer performance and hydraulic characteristics of aluminum foams with different pore densities. The tested aluminium foam samples are of 50.0mm (L) × 25.0mm (W) × 12.0mm (H) in geometric dimensions and pore densities are of 5ppi, 10ppi and 40ppi, respectively. Experiments are performed in forced convective heat transfer using deionized water as the cooling fluid. To minimize the heat loss, the test section is built adiabatically with Teflon and polycarbonate materials. The inlet flow velocity, the temperature distribution on the heating surface and the pressure drop across the metal form are measured. Based on the analysis of experimental data, it is found that convective heat transfer performance in high ppi foam is higher than that in low ppi foam, while the pressure drop shows the opposite trend for a given flow rate.

scholarly journals Convective heat transfer performance of thermal oil-based nanofluids in a high-temperature thermohydraulic loop

2022 ◽  
Vol 171 ◽  
pp. 107243
Author(s):  
Javier Gil-Font ◽  
Nuria Navarrete ◽  
Estefanía Cervantes ◽  
Rosa Mondragón ◽  
Salvador F. Torró ◽  
...  
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Thermal Oil

Convective Heat Transfer Performance of FC-72 in a Pin-Finned Channel

2008 ◽  
Author(s):  
Liang-Han Chien ◽  
S.-Y. Pei ◽  
T.-Y. Wu
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Flow Rate ◽  
Smooth Surface ◽  
Heat Transfer Performance ◽  
Fluid Temperature ◽  
Transfer Performance ◽  
Finned Surface

This study investigates the influence of the heat flux and mass velocity on convective heat transfer performance of FC-72 in a rectangular channel of 20mm in width and 2 mm in height. The heated side has either a smooth surface or a pin-finned surface. The inlet fluid temperature is maintained at 30°C. The total length of the test channel is 113 mm, with a heated length of 25mm. The flow rate varies between 80 and 960 ml/min, and the heat flux sets between 18 and 50 W/cm2. The experimental results show that the controlling variable is heat flux instead of flow rate because of the boiling activities in FC-72. At a fixed flow rate, the pin-finned surface yields up to 20% higher heat transfer coefficient and greater critical heat flux than those of a smooth surface.

Preliminary Investigation on Convective Heat Transfer of Rod Bundle Flow With Spacer Grid for Nuclear Fuel Assembly Application

2015 ◽  
Author(s):  
Chi Young Lee ◽  
Chang Hwan Shin ◽  
Wang Kee In ◽  
Dong Seok Oh ◽  
Tae Hyun Chun
Keyword(s):  
Heat Transfer ◽  
Fuel Assembly ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Heat Transfer Performance ◽  
Axial Flow ◽  
Transfer Performance ◽  
Spacer Grid ◽  
Rod Bundle ◽  
Nuclear Fuel Assembly

The convective heat transfer of rod bundle flow with spacer grid was investigated preliminarily for nuclear reactor core application. As the test fluid, the water was used. To simulate the nuclear fuel assembly, 4×4 rod bundle with P/D (=pitch between rods/rod diameter) of ∼1.35 was prepared together with a spacer grid with twist-mixing vane. A single heated section with five thermocouples embedded in the surface along the circumferential direction was installed around the center subchannel. The measurements of wall temperatures were carried out upstream and downstream of spacer grid. For the rod bundle flow at the inlet of spacer grid (i.e., upstream of spacer grid), the wall temperatures at the gap and subchannel centers exhibited the higher and lower, respectively, which was because in the subchannel center, the axial flow velocity became higher, as compared with the gap center. On the other hand, downstream of spacer grid, the rod wall toward the tip of twist-mixing vane showed the lowest temperature in the measurements along the circumferential direction of rod wall. Near the twist-mixing vane, the averaged wall temperature was observed to be remarkably low, which implies that the twist-mixing vane is an effective tool to enhance the convective heat transfer performance. However, along the axial flow direction behind the spacer grid, the averaged wall temperatures became to increase, and the enhancement of convective heat transfer performance by mixing vane faded away.

An X-lattice cored rectangular honeycomb with enhanced convective heat transfer performance

2020 ◽  
Vol 166 ◽  
pp. 114687 ◽  
Author(s):  
Hongbin Yan ◽  
Qiancheng Zhang ◽  
Weijian Chen ◽  
Gongnan Xie ◽  
Jianjun Dang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Heat Transfer Performance ◽  
Transfer Performance
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