In the work, an analytical study of the efficiency of heat pumps using soil energy for heating, taking into account the climatic conditions of theregion of operation, is performed, which meets the ...tasks of energy saving and allows reducing emissions of harmful substances into the environment. The main attention is paid to increasing the efficiency of utilization of the technical potential of the soil energy source by the heat pump system using vertical soil heat exchangers. A methodology based on use of the mathematical modeling apparatus as a scientifically based toolkit for calculating non-stationary thermal processes, capable of ensuring the stability and reliability of the ground heat pump system in the short and long term, is proposed. The developed toolkit for calculation and analysis of heat exchange processes allows determining the power of the heat flow, which is removed from the soil, taking into account changes in climatic factors, temperature distribution in the soil around the soil tube and along its length over time, schematic and structural features of the soil tubes for further optimization of the parameters of the heat pump system . It was established that the power of the heat flow, which enters the evaporator of the heat pump from vertical soil pipes, depends on a number of influencing factors: the flow regime of the working fluid circulating in the soil circuit; physical properties of the working body; number of soil heat exchangers; temperature distribution in the soil around the soil tube along its entire length, which changes significantly during long-term operation of the system, affecting the course of heat exchange processes in the system elements. The proposed method makes it possible to perform numerical modeling of thermal processes in the elements of the heat pump, to determine the energy efficiency of the ground heat pump system, which is able to reliably provide consumers with heat during a long period of operation, which can be considered an innovative approach to the analysis of prospects for the development of heat pump heat supply.
In the article analytical studies of the efficiency of heat pumps in the thermal schemes of thermal and nuclear power plants for centralized heating and hot water supply systems taking into account ...the climatic conditions of Ukraine have been carried out. This task meets the objectives of energy saving and reduces emissions of harmful substances into the environment. The main focus is on improving the efficiency of the heat pump power supply system, which integrates an alternative energy source. An analysis of the exergy parameters of heat pump cycles has been performed, which have made it possible to establish that the most efficient working fluid of the cycle is freon R152a, at which the highest heat pump conversion coefficient and the lowest compressor power indicator are achieved. Ways and methods leading to reduction to underproduction of the electricity by turbine of of power plant and to increasation of the efficiency of a steam turbine cycle are proposed. It is shown that the efficiency of the system is most affected by losses in the evaporator, so the efficiency of this element of the heat pump should be given the most attention when using the energy of circulating water. An additional aspect of the novelty of the proposed method lies in the possibility of further optimization of the technical and economic parameters of the power system. A methodology based on the use of the exergy method of analysis to substantiate the conditions for the rational use of heat pumps for power plants in the utilization of low-grade heat of circulating water for cooling the turbine condensers is proposed, which can be considered as innovative way. Results open the further prospects for the development of heat pump heat supplyhas been proposed.
One of the basic directions of perfection of heat supply systems is the tendency of transition to the low-temperature heating systems based on application of heat pump installations. We consider heat ...supply system with heat pump installations using subsoil waters. Numerical simulation of thermal processes in the elements of a single-stage and double-stage heat pump systems has been worked out. Values of depths of wells and their quantity, necessary for effective operation of the offered installations, and values of capacity of electric water pumps for subsoil waters unit are calculated. Capacity of compressor electric drive and coefficient of performance of heat pump for the conditions of the city of Odessa are presented.
Removal of groundwater with further use of it for potable water supply and heat supply with the use of heat pump is an important problem. A new revolutionary approach to the decision of energy and ...water saving that provides rational accommodation of groundwater boreholes ensuring the required flow rate of water through the heat pump evaporator with simultaneously high intensity of heat exchange process is proposed. The method of calculation which allows determining the necessary depth of borehole, quantity of boreholes, in consideration of flow rate and temperature of subsoil water determining capacity of heat pump installation is worked out.
The basic directions for perfection heat supply systems are the tendency of transition to the low-temperature heating systems based at application heat pump installations. We consider heat supply ...systems with ground-source heat pump. The paper considers modeling the efficiency of ground-source heat pumps with the account of Ukrainian climate conditions. The paper presents the energy performance criteria which show the way to rational implementation of ground-source heat pumps for heating. A computational model based at non-stationary heat exchange processes in elements of ground-source heat pumps is developed. Generalization and analysis of theoretical and experimental dates allow establishing nature of dependence thermophysical properties on temperature insoil around ground heat exchangers during long term operation of the system. Numerical simulation of thermal processes in vertical ground pipes for ground-source heat pump working with low-temperature heating systems has been worked out. The results of numerical modeling demonstrated perfection and technical adaption of ground-source heat pump for low-temperature heating systems with rational using ground energy potential. The novelty of our method is complex usage theoretical and experimental results which enable to prevent freezing in the ground during long term exploitation This provides insights at effects of different resource mixes and may serve as a new approach to analysis of future heat pump systems using ground source energy development.The proposed method contributes to the field of creation and implementation the sustainable heating technologies using renewable energy sources. The ground heat exchange pipes quantities that are necessary for effective operation heat pump installation, capacity and coefficient of performance with the account of climate conditions are calculated.
This article is devoted to the methods for perfection of energy, economic factors, environ-mental factors and work modes of the ground source heat pump systems with the account of climate conditions. ...The purpose of the work is to predict and prevent freezing of the soil during long term of exploitation of the low-power and high-power ground source heat pump systems for justifying rational conditions of implementation GSHP in Ukraine and South-East Regions of Europe. This goal is achieved by solving the following problems: determining the energy-economic and environmental factors based on considering the work modes of the ground source heat pumps; evaluation of the operating efficiency of ground source heat pump systems based on minimizing fuel consumption and green-house gas emissions; perfection of solutions enable implementation of ground source heat pumps friendly to the environment and justifying rational conditions of implementation the ground source heat pumps for residential sector. The important results of the work are the obtained and analyzed data on the influence of energy and economic factors both environmental criteria on the work modes and scheme-constructive solutions of ground source heat pumps. Modeling of heat exchange processes in the soil around the soil tube shows that in order to avoid freezing of the soil, the minimum permissible specific number of vertical tubes should be at least 0.12–0.15 pieces/m2 of heated area. The significance of the results consists in the possibility of using the results of numerical simulation for preventing freezing of the soil around ground pipes of the ground source heat pump systems.
As a research result, characteristic indicators of the efficiency of using various heat sources in combined heat supply systems were determined. During the study, various schemes for integrating heat ...accumulators in heat supply systems were considered. Water was used as a battery, which also acts as a coolant. Mathematical modeling of processes in combined heat supply systems using intermittent heating is carried out. The characteristic operating modes of the elements of heat supply systems that take into account the operating modes of heat consumers are determined. Mathematical modeling was carried out using a software package that allows to obtain the distribution of heat power of the heat supply system by its main elements and its characteristic operation modes. According to the research results, a coefficient of thermal power reduction and a coefficient of efficiency of using the heat accumulator volume were proposed. These coefficients allow to evaluate the efficiency of heat sources and the efficiency of using the volume of the heat storage tank. Based on the obtained data, the task was set to optimize the daily load of the heat source, taking into account the installation of the storage tank.
The research results can be used for the reconstruction of heat supply systems of buildings with a two-period operation mode (operation duty) using both traditional and renewable heat sources. This will significantly increase the efficiency of the use of elements of the heat supply system, even out the daily heat generation schedule and increase the service life of the main equipment
As a result of research, the conditions for the effective use of the volume of heat accumulator based on solid materials were determined. In the course of research, various schemes of the device of ...tubular heating elements for charging the channel elements of the heat accumulator were considered. Fire clay was used as a heat-accumulating material, capable of operating in a wide temperature range (up to 600 °С). Mathematical modeling of temperature change in the process of discharge over the cross section of the heat-accumulating unit has been carried out. Mathematical modeling was carried out using an application package that allows to obtain the temperature distribution over the cross section of the heat accumulator at key points of its work. The obtained simulation results were tested on an experimental setup consisting of four heat-accumulating units during the charging process and during the discharge of the heat accumulator. According to the research results, the most effective layout of the heating elements was determined, which allows to make the most of the volume of the heat-accumulating material. The dependencies to determine the exponent and the averaging coefficient of the heat flux are also found, which allow a more rational use of the volume of the accumulating nozzle.
The research results can be used to reconstruct decentralized heat supply systems for both residential buildings and public buildings. This will significantly align the schedule of electricity consumption during the day and reduce the consumption of hydrocarbon fuels.
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