An analytical model for transient heat transfer in ground-coupled heat exchangers of closed-loop geothermal systems

2019 ◽  
Vol 150 ◽  
pp. 696-705 ◽  
Author(s):  
Seyed Ali Ghoreishi-Madiseh ◽  
Ali Fahrettin Kuyuk ◽  
Marco Antonio Rodrigues de Brito
Keyword(s):  
Heat Transfer ◽  
Analytical Model ◽  
Heat Exchangers ◽  
Closed Loop ◽  
Transient Heat Transfer ◽  
Geothermal Systems

The Effect of Gravity on Heat Transfer by Rayleigh Streaming in Pulse Tubes and Thermal Buffer Tubes

2004 ◽  
Author(s):  
Konstantin I. Matveev ◽  
Scott Backhaus ◽  
Gregory W. Swift
Keyword(s):  
Heat Transfer ◽  
Analytical Model ◽  
Thermal Energy ◽  
Heat Exchangers ◽  
Acoustic Energy ◽  
Heat Leak ◽  
Thermoacoustic Engines ◽  
Different Temperatures ◽  
Rayleigh Streaming ◽  
Streaming Flow

Thermoacoustic engines and refrigerators use the interaction between heat and sound to produce acoustic energy or to transport thermal energy. Heat leaks in thermal buffer tubes and pulse tubes, components in thermoacoustic devices that separate heat exchangers at different temperatures, reduce the efficiency of these systems. At high acoustic amplitudes, Rayleigh mass streaming can become the dominat means for undesirable heat leak. Gravity affects the streaming flow patterns and influences streaming-induced heat convection. A simplified analytical model is constructed that shows gravity can reduce the streaming heat leak dramatically.

Transient Heat Transfer in a Vapor-Heated Heat Exchanger With Arbitrary Timewise-Variant Flow Perturbation

1964 ◽  
Vol 86 (2) ◽  
pp. 133-142 ◽  
Author(s):  
Wen-Jei Yang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Heat Exchangers ◽  
Amplitude Ratio ◽  
Perturbation Technique ◽  
Transient Heat Transfer ◽  
Coolant Temperature ◽  
Flow Perturbation

An analysis is made of transient heat transfer in a vapor-heated heat exchanger with an arbitrary timewise-variant flow perturbation. The heat-transfer coefficient between the tube and coolant is assumed to vary like the n power of the coolant velocity. Results are obtained through the use of the perturbation technique. General relations are presented in closed form and their application is illustrated by carrying out some typical examples: step, linear, exponential, and sinusoidal transients in the coolant flow velocity. The influence of the system parameters on the variation of the coolant temperature is investigated. A phenomenon of resonance in the amplitude-ratio and phase-shift is disclosed for the oscillating flow transient. This phenomenon is explained by analyzing the enthalpy change of the coolant particle in the heat exchanger. The results are also compared with the analyses that have assumed a constant heat-transfer coefficient. Heat exchangers to which these results apply include the double-pipe and shell- and-tube type heat exchangers.

Transient Heat Transfer Analysis of a Micro Heat Exchanger

2013 ◽  
Vol 455 ◽  
pp. 330-334 ◽  
Author(s):  
Zhong Qian ◽  
Hai Min Wang
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Heat Exchanger ◽  
Silicon Nitride ◽  
Heat Exchangers ◽  
Three Dimensional ◽  
Heat Fluxes ◽  
Heat Transfer Analysis ◽  
Transient Heat Transfer ◽  
Micro Heat Exchanger

The research object is a micro heat exchanger (MHT) applied in chip cooling, a three dimensional simulation model is developed to analyze the transient heat transfer of the exchanger according to both exponential and periodic heat fluxes. Based on the computational results of the profiles of temperature and thermal stress, a comparison of performance of heat exchangers made of copper and silicon nitride compound is carried out. The results indicate that the capability of a copper heat exchanger is better than that of a silicon nitride exchanger under low load working condition due to the excellent thermal conductivity of copper. However, with large load fluctuations, the advantage of structure strength of compound makes the exchanger attractive since it has lower thermal stress and could guarantee a long-term stability. The efforts of this paper are referable for further research and development of micro heat exchangers.

scholarly journals New tools to support the designing of efficient and reliable ground source heat exchangers: the Cheap-GSHPs databases and maps

2019 ◽  
Vol 49 ◽  
pp. 47-55 ◽  
Author(s):  
Antonio Galgaro ◽  
Giorgia Dalla Santa ◽  
Michele De Carli ◽  
Giuseppe Emmi ◽  
Angelo Zarrella ◽  
...  
Keyword(s):  
Heat Exchangers ◽  
Closed Loop ◽  
Geothermal Systems ◽  
Historical Buildings ◽  
Paper Briefly ◽  
Heating And Cooling ◽  
Ground Source ◽  
Eu Project ◽  
Installation Cost ◽  
The Eu

Abstract. The final aim of the EU funded Cheap-GSHPs project is to reduce the total installation cost of closed-loop shallow geothermal systems. As part of the project a Decision Support System (DSS) has been developed and released on the web, in order to support the design of new closed-loop geo-exchange systems. The Cheap-GSHP project addresses all the aspects involved in planning and dimensioning a new borefield and therefore, the DSS is composed of several databases and tools that collect and elaborate the preliminary data and information that are necessary during the sizing phase, such as the geological and drilling aspects as well as the heating and cooling building demand. This paper briefly introduces the content of the databases and the mapping methodology developed for the Cheap-GSHPs DSS. All these researches are further deepen in the EU project GEO4CIVHIC, with a special attention to the application of shallow geothermal systems for building conditioning to historical buildings.

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