scholarly journals Effect of Borehole Material on Analytical Solutions of the Heat Transfer Model of Ground Heat Exchangers Considering Groundwater Flow

Energies ◽  
2016 ◽  
Vol 9 (5) ◽  
pp. 318 ◽  
Author(s):  
Sangwoo Park ◽  
Seokjae Lee ◽  
Hyobum Lee ◽  
Khanh Pham ◽  
Hangseok Choi
Keyword(s):  
Heat Transfer ◽  
Groundwater Flow ◽  
Analytical Solutions ◽  
Heat Exchangers ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Ground Heat Exchangers

scholarly journals Numerical modelling of vertical borehole heat exchangers performance under Lithuanian Quaternary conditions

Baltica ◽  
2019 ◽  
Vol 31 (2) ◽  
pp. 146-153
Author(s):  
Audrius Indriulionis ◽  
Žygimantas Palaitis ◽  
Petras Šinkūnas ◽  
Robert Mokrik
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Groundwater Flow ◽  
Heat Exchangers ◽  
Heat Transfer Model ◽  
Capital City ◽  
Transfer Model ◽  
Practical Tool ◽  
Borehole Heat Exchangers ◽  
Vertical Borehole

The vertical borehole heat exchangers were surrounded by the heterogeneous multilayered geological environment and groundwater flow that affected the performance of borehole plants. In this paper, the field investigation of vertical borehole ground heat exchangers in capital city Vilnius (Visoriai), Lithuania is presented. The numerical heat transfer model considering seven different geological strata was developed using the cylindrical heat sink model for vertical borehole inside by solving the soil mass and heat transfer equations with groundwater flow. The numerical multilayered ground vertical borehole heat transfer model was calculated and validated by in-situ thermal response test data. The numerical model results were also compared with the homogeneous finite difference model expressed by the temperature response functions (well known as “g-functions”). The practical realization of g-functions was designed in the Earth Energy Designer as a practical tool for geoengineers designing the vertical borehole plants. The temperature profiles at borehole wall at different heating times were presented and explored together with relative errors. The numerical model will be used as a practical tool for the Lithuanian Geological Survey under the Ministry of Environment to estimate the underground conditions for the consumption of shallow geothermal energy.

Transient Temperature Response of Variable Flow Heat Exchangers in a Marnoch Heat Engine

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
P. Saneipoor ◽  
G. F. Naterer ◽  
I. Dincer
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Heat Engine ◽  
Heat Transfer Model ◽  
Transient Temperature ◽  
Transfer Model ◽  
Gas Temperature ◽  
Variable Flow ◽  
Flow Heat ◽  
Shell And Tube

Within a Marnoch heat engine (MHE), a water/glycol mixture transfers heat from the heat source into a set of variable flow heat exchangers and removes heat from adjoining cold heat exchangers. The compressed dry air is used as the working medium in this heat engine. The MHE has four shell and tube heat exchangers, which operate transient and variable flow conditions. A new transient heat transfer model is developed to predict this transient behavior of the heat exchangers for different flow regimes and temperatures. The results from the model are validated against experimental results from an MHE prototype. The heat transfer model shows 85% agreement with measured data from the MHE prototype for the individual heat exchangers. This model can be used for similar shell and tube heat exchangers with straight or U-shaped tubes. The heat transfer model predicts the gas temperature on the shell side, when a step change is imposed on the liquid entering the tubes.

Theoretical Post-Dryout Heat Transfer Model

2018 ◽  
Vol 1 (1) ◽  
pp. 142-150
Author(s):  
Murat Tunc ◽  
Ayse Nur Esen ◽  
Doruk Sen ◽  
Ahmet Karakas
Keyword(s):  
Heat Transfer ◽  
Droplet Diameter ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Operating Pressure ◽  
Vertical Pipe ◽  
Two Phase ◽  
Experimental Values ◽  
Reactor Operating ◽  
Coolant System

A theoretical post-dryout heat transfer model is developed for two-phase dispersed flow, one-dimensional vertical pipe in a post-CHF regime. Because of the presence of average droplet diameter lower bound in a two-phase sparse flow. Droplet diameter is also calculated. Obtained results are compared with experimental values. Experimental data is used two-phase flow steam-water in VVER-1200, reactor coolant system, reactor operating pressure is 16.2 MPa. On heater rod surface, dryout was detected as a result of jumping increase of the heater rod surface temperature. Results obtained display lower droplet dimensions than the experimentally obtained values.

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