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Abstract

The paper presents results of a parametric analysis of a hightemperature nuclear-reactor cogeneration system. The aim was to investigate the power efficiency of the system generating heat for a high-temperature technological process and electricity in a Brayton cycle and additionally in organic Rankine cycles using R236ea and R1234ze as working fluids. The results of the analyses indicate that it is possible to combine a 100 MW high-temperature gas-cooled nuclear reactor with a technological process with the demand for heat ranging from 5 to 25 MW, where the required temperature of the process heat carrier is at the level of 650°C. Calculations were performed for various pressures of R236ea at the turbine inlet. The cogeneration system maximum power efficiency in the analysed cases ranges from ~35.5% to ~45.7% and the maximum share of the organic Rankine cycle systems in electric power totals from ~26.9% to ~30.8%. If such a system is used to produce electricity instead of conventional plants, carbon dioxide emissions can be reduced by about 216.03–147.42 kt/year depending on the demand for process heat, including the reduction achieved in the organic Rankine cycle systems by about 58.01–45.39 kt/year (in Poland).
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Authors and Affiliations

Julian Jędrzejewski
1
Małgorzata Hanuszkiewicz-Drapała
2

  1. Antea Polska S.A., Duleby 5, 40-833 Katowice, Poland
  2. Silesian University of Technology, Faculty of Energy and Environmental Engineering, Konarskiego 18, 44-100 Gliwice, Poland
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Abstract

In the paper a heating system with a vapour compressor heat pump and vertical U-tube ground heat exchanger for small residential house is considered. A mathematical model of the system: heated object - vapour compressor heat pump - ground heat exchanger is presented shortly. The system investigated is equipped, apart from the heat pump, with the additional conventional source of heat. The processes taking place in the analyzed system are of unsteady character. The model consists of three elements; the first containing the calculation model of the space to be heated, the second - the vertical U-tube ground heat exchanger with the adjoining area of the ground. The equations for the elements of vapour compressor heat pump form the third element of the general model. The period of one heating season is taken into consideration. The results of calculations for two variants of the ground heat exchanger are presented and compared. These results concern variable in time parameters at particular points of the system and energy consumption during the heating season. This paper presents the mutual influence of the ground heat exchanger subsystem, elements of vapour compressor heat pump and heated space.

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Authors and Affiliations

Małgorzata Hanuszkiewicz-Drapała
Jan Składzień
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Abstract

This paper presents the results of thermodynamic analyses of a system using a horizontal ground heat exchanger to cool a residential building in summer and heat it in the autumn-winter period. The main heating device is a vapour compression heat pump with the ground as the lower heat source. The aim of the analyses is to examine the impact of heat supply to the ground in the summer period, when the building is cooled, on the operation of the heating system equipped with a heat pump in the next heating season, including electricity consumption. The processes occurring in cooling and heating systems have an unsteady nature. The main results of the calculations are among others the time-dependent values of heat fluxes extracted from or transferred to the ground heat exchanger, the fluxes of heat generated by the heat pump and supplied to the heated building by an additional heat source, the parameters in characteristic points of the systems, the temperature distributions in the ground and the driving electricity consumption in the period under analysis. The paper presents results of analysis of cumulative primary energy consumption of the analyzed systems and cumulative emissions of harmful substances.

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Authors and Affiliations

Małgorzata Hanuszkiewicz-Drapała
Tomasz Bury
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Abstract

A cross-flow, tube and fin heat exchanger of the water – air type is the subject of the analysis. The analysis had experimental and computational form and was aimed for evaluation of radiative heat transfer impact on the heat exchanger performance. The main element of the test facility was an enlarged recurrent segment of the heat exchanger under consideration. The main results of measurements are heat transfer rates, as well as temperature distributions on the surface of the first fin obtained by using the infrared camera. The experimental results have been next compared to computational ones coming from a numerical model of the test station. The model has been elaborated using computational fluid dynamics software. The computations have been accomplished for two cases: without radiative heat transfer and taking this phenomenon into account. Evaluation of the radiative heat transfer impact in considered system has been done by comparing all the received results.

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Authors and Affiliations

Małgorzata Hanuszkiewicz-Drapała
Tomasz Bury
Katarzyna Widziewicz

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