Numerical Analysis on the Heat Transfer Characteristics of the Radiator in a Heating Room

2014 ◽  
Vol 501-504 ◽  
pp. 2307-2310
Author(s):  
Ye Wang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Outer Wall ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Important Means ◽  
Weak Influence

Natural convective heat transfer is the most important means to supply heat load for resident building to keep necessary indoor air temperature in winter. To determine the surface convective heat transfer coefficient (CHTC) of a radiator is of primary importance to evaluate the heat flow within building interiors, and thereby to affect the thermal comfort and the overall energy consumption of a building. In this paper, a turbulent k-ε model is used to numerically analyze the heat transfer characteristics of a radiator used in a heating room in Lanzhou region of China. The results indicate that the averaged Nu number of radiator surface increases with increasing outer wall thermal conductivity, decreasing outdoor temperature and decreasing radiator surface area, respectively. And the outer wall thermal conductivity has weak influence on the local Nu number of radiator surface.

Boiling and Convective Heat Transfer Characteristics of Nanofluids

2011 ◽  
Vol 110-116 ◽  
pp. 393-399
Author(s):  
S.M. Sohel Murshed ◽  
C.A. Nieto de Castro ◽  
M.J.V. Lourenço ◽  
M.L.M. Lopes ◽  
F.J.V. Santos
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Potential Applications

Nanofluids have attracted great interest from researchers worldwide because of their reported superior thermal performance and many potential applications. However, there are many controversies and inconsistencies in reported experimental results of thermal conductivity, convective heat transfer coefficient and critical heat flux of nanofluids. In this paper, two major features of nanofluids, which are boiling and convective heat transfer characteristics are presented besides critically reviewing recent research and development on these areas of nanofluids.

Heat Transfer Characteristics of Nano-Fluids

2013 ◽  
Vol 757 ◽  
pp. 175-195 ◽  
Author(s):  
Ritu Gupta ◽  
Parminder Singh ◽  
R.K. Wanchoo
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Future Research ◽  
Potential Candidate ◽  
Next Generation ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

Nanofluids are engineered colloids made of a base fluid and nanoparticles, which become potential candidate for next generation heat transfer medium. Nanofluids have higher thermal conductivity and single-phase heat transfer coefficients than their base fluids. The use of additives is a technique applied to enhance the heat transfer performance of base fluids. Recent articles address the unique features of nanofluids, such as enhancement of heat transfer, improvement in thermal conductivity, increase in surface volume ratio, Brownian motion, thermophoresis, etc. A complete understanding about the heat transfer enhancement in forced convection in laminar and turbulent flow with nanofluids is necessary for the practical applications. There are many controversies and inconsistencies in reported arguments and experimental results on various thermal characteristics such as effective thermal conductivity, convective heat transfer coefficient and boiling heat transfer rate of nanofluids. As of today, researchers have mostly focused on anomalous thermal conductivity of nanofluids. Although investigations on boiling, droplet spreading, and convective heat transfer are very important in order to exploit nanofluids as the next generation coolants, considerably less efforts have been made on these major features of nanofluids. This review summarizes recent research on fluid flow and heat transfer characteristics of nanofluids in forced and free convection flows and identifies opportunities for future research.

Experimental Convective Heat Transfer With Nanofluids

2008 ◽  
Author(s):  
S. Kabelac ◽  
K. B. Anoop
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Turbulent Regime ◽  
Heat Transfer Characteristics ◽  
Forced Convective Heat Transfer ◽  
Transfer Characteristics

Nanofluids are colloidal suspensions with nano-sized particles (<100nm) dispersed in a base fluid. From literature it is seen that these fluids exhibit better heat transfer characteristics. In our present work, thermal conductivity and the forced convective heat transfer coefficient of an alumina-water nanofluid is investigated. Thermal conductivity is measured by a steady state method using a Guarded Hot Plate apparatus customized for liquids. Forced convective heat transfer characteristics are evaluated with help of a test loop under constant heat flux condition. Controlled experiments under turbulent flow regime are carried out using two particle concentrations (0.5vol% and 1vol %). Experimental results show that, thermal conductivity of nanofluids increases with concentration, but the heat transfer coefficient in the turbulent regime does not exhibit any remarkable increase above measurement uncertainty.

scholarly journals Experimental Study on the Flow and Heat Transfer of Graphene-Based Lubricants in a Horizontal Tube

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1675
Author(s):  
Zhongpan Cai ◽  
Maocheng Tian ◽  
Guanmin Zhang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Horizontal Tube ◽  
Lubricating Oil ◽  
Heat Transfer Characteristics ◽  
Experiment Platform ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer

To improve the heat transfer characteristics of lubricant, graphene-based lubricants were prepared by adding graphene particles, due to its advantages of excellent thermal conductivity and two-dimensional sheet structure. In the present study, its physical properties were measured. A flow heat transfer experiment platform was built to study the flow and heat transfer characteristics of the graphene lubricating oil in a horizontal circular tube. The results show that the graphene lubricant prepared using a two-step approach had good stability, and the dispersibility was good without the agglomeration phenomenon, according to measurements undertaken using an electron microscope and centrifuge. The thermal conductivity and viscosity of graphene lubricant increased with the increase of the graphene concentration, and the thermal conductivity of graphene lubricant with the same concentration decreased with the increase of temperature. When the concentration was equal, the convective heat transfer Nusselt number (Nu) of graphene lubricant increased with the increase of Reynolds number (Re). When Re was equal, the convective heat transfer Nu increased with the increase of graphene particle concentration, and the maximum Nu increased by 40%.

Numerical Analysis of Heat Transfer Characteristics for Supercritical Aviation Kerosene

2015 ◽  
Author(s):  
Yachao Song ◽  
Danjiao Ma ◽  
Jingzhi Zhang ◽  
Jing-xiang Chen ◽  
Songze Chen ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Experimental Result ◽  
Heating Process ◽  
Heat Transfer Characteristics ◽  
Aviation Kerosene ◽  
Transfer Characteristics

With the physical property changing dramatically, the supercritical aviation kerosene obtains unique heat transfer characteristics. In this way, it is difficult to investigate the heat transfer characteristics by normal experiment and therefore we resort to numerical analysis to address the scientific questions in this study. The project is proposed to demystify the heat transfer characteristics of supercritical aviation kerosene with CFD in 4mm inside diameter vertical circular tubes. Under the conditions of different pressures (3.5MPa-5MPa), the physical properties of the fluid are expressed in linear poly-nominal fitting including density, isobaric specific heat, thermal conductivity and viscosity. With the guidance of CFD, we analyze how the heat transfer characteristics can be affected by the value of temperature, pressure, heat flux mass velocity and so on. The result indicates: (1) In primary heating process, convective heat transfer is enhanced significantly. (2) When wall temperature surpasses the critical temperature, heat transfer can be deteriorated. (3) When the temperature continues to go up, the convective heat transfer coefficient will rise greatly again. Furthermore, the project has also compared the numerical analysis result with experimental result, which shows good agreement with each other. Hence, the validation of numerical analysis of supercritical fluid is well recognized.

Experimental Investigation on Heat Transfer Characteristics of CO2-Based Foam Fracturing Fluid

2013 ◽  
Vol 805-806 ◽  
pp. 1278-1282
Author(s):  
Ze Feng Jing ◽  
Shu Zhong Wang ◽  
Xiang Rong Luo
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Shear Rate ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Heat Transfer Characteristics ◽  
Fracturing Fluid ◽  
Transfer Characteristics

Heat transfer characteristics of the CO2-based foam fracturing fluid were investigated on the large-scale test loop of foam fracturing fluid. The relationship between thermal conductivity coefficient and shear rate was introduced into the expression of the convective heat transfer coefficient. Thus the expression of the convective heat transfer coefficient of power-law fluid was revised. The results show that the convective heat transfer coefficient of the fracturing fluid increases with the increase of the pressure, the foam quality and the shear rate. The convective heat transfer coefficient of the foam fracturing fluid calculated by the revised calculation formula is highly consistent with the experimental data at low pressure. The deviation is bigger at high pressure, but still within 20%.

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