scholarly journals Thermal Performance Investigation of Heat Transfer Characteristics of a Two Phase Thermosyphon using Hybrid Nanofluid

2011 ◽  
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Hybrid Nanofluid ◽  
Heat Transfer Characteristics ◽  
Two Phase ◽  
Transfer Characteristics

CO2-Filled Vertical Geothermal Boreholes: Modeling and Application

2013 ◽  
Author(s):  
Parham Eslami-Nejad ◽  
Mohamed Ouzzane ◽  
Zine Aidoun
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Thermal Performance ◽  
Heat Pumps ◽  
Superior Performance ◽  
Fluid Temperature ◽  
Heat Transfer Characteristics ◽  
Two Phase ◽  
Transfer Characteristics ◽  
Heating And Cooling

In the context of extremely cold or hot climates, ground coupled heat pumps offer several environmental and energy efficiency advantages over conventional methods for heating and cooling of buildings and they are increasingly used in most near-zero and net-zero energy buildings. However, the high initial cost of the ground loop portion (geothermal boreholes) has often raised the question on the economical competitiveness of the system. In the present study, a geothermal borehole is proposed in which two-phase carbon dioxide (mixture of liquid and vapor) exchanges heat with the ground to improve the thermal performance of the borehole and thus to reduce borehole length. Carbon dioxide shows several cost and environmental advantages. Moreover, it offers superior thermophysical properties and heat transfer characteristics. A numerical model has been developed to study the complex thermal behavior of a two-phase CO2-filled vertical geothermal borehole. The model can handle both two-phase and single-phase conditions along the borehole length. An explicit solution for fully coupled conservation equations of mass, momentum and energy as well as an equation of state are applied. The model accounts for the thermal interaction among the pipes and it predicts the fluid temperature, pressure and two-phase quality profiles. It is used to assess the thermal performance of the CO2-filled secondary loop geothermal borehole operating in heating mode. Results indicate that the proposed borehole offers superior performance due to the relatively high two-phase heat transfer characteristics of CO2.

scholarly journals Experimental study on heat transfer characteristics of a modified two-phase closed thermosyphon

2017 ◽  
Vol 21 (6 Part A) ◽  
pp. 2481-2489 ◽  
Author(s):  
Babak Aghel ◽  
Masoud Rahimi ◽  
Saeed Almasi
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Experimental Study ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Working Fluid ◽  
Heat Transfer Characteristics ◽  
Two Phase ◽  
Transfer Characteristics ◽  
Adiabatic Section

This study investigated the heat transfer characteristics of modified two-phase closed thermosyphon (TPCT) using water as the working fluid. In the modified TPCT, to reduce thermal resistance, a small TPCT was inserted inside the adiabatic section. For both the plain and modified thermosyphons the performances were determined at various heat inputs from 71-960 W. The results showed that the modified TPCT had less temperature difference between the evaporator and condenser sections than the plain one. According to the experimental data, in the modified TPCT, the thermal performance increased up to 20% over that of the unmodified one.

Thermal performance of inserting hybrid nanofluid in parabolic trough collector

2021 ◽  
Author(s):  
Otabeh Al-Oran ◽  
Ferenc Lezsovits
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Thermal Performance ◽  
Hybrid Nanofluid ◽  
Heat Transfer Characteristics ◽  
Parabolic Trough ◽  
Transfer Coefficients ◽  
Parabolic Trough Collector ◽  
Heat Transfer Coefficients ◽  
Transfer Characteristics

AbstractIn this work, the thermal performance of using hybrid nanofluid of Ceria oxide and multi-walled carbon nanotube-based MOL 68 in the receiver tube of parabolic trough collector is simulated numerically. The influence of using this nanofluid under various volume concentrations and different Reynold numbers is solved numerically using computational fluid dynamics. The turbulent model's analysis is carried out based on k–ϵ re-normalization group and employed to find the Nusselt number and the heat transfer coefficients. The model results were validated with the previous correlation, which were used to evaluate the Nusselt number. The results showed that hybrid nanofluid enhances the heat transfer characteristics of the parabolic trough collector in comparison with the base fluid. Furthermore, even better heat transfer characteristics can be achieved with an increased volume concentration of the modified nanofluids.

Maximizing Heat Transfer Through Joint Fin Systems

2005 ◽  
Vol 128 (2) ◽  
pp. 203-206 ◽  
Author(s):  
A.-R. A. Khaled
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Performance ◽  
Critical Length ◽  
The Other ◽  
Rigid Fixation ◽  
Convection Coefficient ◽  
Heat Transfer Characteristics ◽  
Cold Side ◽  
Transfer Characteristics

Heat transfer through joint fins is modeled and analyzed analytically in this work. The terminology “joint fin systems” is used to refer to extending surfaces that are exposed to two different convective media from its both ends. It is found that heat transfer through joint fins is maximized at certain critical lengths of each portion (the receiver fin portion which faces the hot side and the sender fin portion that faces the cold side of the convective media). The critical length of each portion of joint fins is increased as the convection coefficient of the other fin portion increases. At a certain value of the thermal conductivity of the sender fin portion, the critical length for the receiver fin portion may be reduced while heat transfer is maximized. This value depends on the convection coefficient for both fin portions. Thermal performance of joint fins is increased as both thermal conductivity of the sender fin portion or its convection coefficient increases. This work shows that the design of machine components such as bolts, screws, and others can be improved to achieve favorable heat transfer characteristics in addition to its main functions such as rigid fixation properties.

Evaporation of Single Drops of n-Pentane/n-Hexane Mixtures in Water

1992 ◽  
Vol 114 (4) ◽  
pp. 965-971 ◽  
Author(s):  
H. Shimaoka ◽  
Y. H. Mori
Keyword(s):  
Heat Transfer ◽  
Temperature Difference ◽  
Vapor Bubble ◽  
Experimental Results ◽  
Rise Velocity ◽  
Heat Transfer Characteristics ◽  
Two Phase ◽  
Transfer Characteristics ◽  
Preceding Work ◽  
Liquid Vapor

The evaporation of isolated drops (2.1−3.0 mm diameter) of nonazeotropic n-pentane/n-hexane mixtures in the medium of water was observed under pressures of 0.11−0.46 MPa and temperature differences up to 27 K. The mole fractions of n-pentane, x, in the mixtures were set at 0.9, 0.5, 0.1, and 0, to be completed by the condition x = 1 set in a preceding work (Shimaoka and Mori, 1990). Experimental results are presented in terms of the instantaneous rise velocity of, and an expression of instantaneous heat transfer to, each drop evaporating and thereby transforming into a liquid/vapor two-phase bubble and finally into a vapor bubble. The dependencies of the heat transfer characteristics on the pressure, the temperature difference, and x are discussed.

Sign in / Sign up

Export Citation Format

Share Document