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## Mathematical modelling of thermal and flow processes in vertical ground heat exchangers

### Abstract

The main task of mathematical modelling of thermal and flow processes in vertical ground heat exchanger (BHE-Borehole Heat Exchanger) is to determine the unit of borehole depth heat flux obtainable or transferred during the operation of the installation. This assignment is indirectly associated with finding the circulating fluid temperature flowing out from the U-tube at a given inlet temperature of fluid in respect to other operational parameters of the installation. The paper presents a model of thermal and flow processes in BHE consisting of two analytical models separately-handling processes occurring inside and outside of borehole. A quasi-three-dimensional model formulated by Zeng was used for modelling processes taking place inside the borehole and allowing to determine the temperature of the fluid in the U-tube along the axis of BHE. For modelling processes occurring outside the borehole a model that uses the theory of linear heat source was selected. The coupling parameters for the models are the temperature of the sealing material on the outer wall of the borehole and the average heat flow rate in BHE. Experimental verification of the proposed model was shown in relation to BHE cooperating with a heat pump in real conditions.
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## Exergetic Analysis For A Complete Node Of Fluidised-Bed Drying Of Poppy Seeds

### Abstract

The article presents an experimental-theoretical analysis of fluidised-bed drying of poppy seeds directed on minimisation of energy. The analysis was performed for a complete drying node incorporating a heat exchanger and a fan. Two complementary factors were used in the exergetic evaluation: exergy efficiency and unit consumption of exergy. An analysis of drying in stationary bed was carried out for comparison purposes. Results of the exergetic analysis can become a basis for innovative works focused on decreasing energy consumption of a technological node being analysed, e.g. by the use of recirculation of fluidising-drying medium.
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