The article addresses the issues falling within the scope of the economic analysis of a detached building’s heating system with a direct evaporation ground source heat pump installation. The paper was elaborated based on the data made available by the investment’s contractor and the investor. The paper provides data on the investment expenditures and utility cost, calculations of the installation payback, internal return rate and the current net value.

The analyzed heat accumulator is a key element in a hybrid heating system. In this paper, analytical and numerical models of the ceramic heat accumulator are presented.The accuracy of finite difference methods will be assessed by comparing the results with those obtained from the exact analytical solution.

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.

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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Exergy analysis of low temperature geothermal heat plant with compressor and absorption heat pump was carried out. In these two concepts heat pumps are using geothermal water at 19.5°C with spontaneous outflow 24 m3/h as a heat source. The research compares exergy efficiency and exergy destruction of considered systems and its components as well. For the purpose of analysis, the heating system was divided into five components: geothermal heat exchanger, heat pump, heat distribution, heat exchanger and electricity production and transportation. For considered systems the primary exergy consumption from renewable and non-renewable sources was estimated. The analysis was carried out for heat network temperature at 50/40°C, and the quality regulation was assumed. The results of exergy analysis of the system with electrical and absorption heat pump show that exergy destruction during the whole heating season is lower for the system with electrical heat pump. The exergy efficiencies of total system are 12.8% and 11.2% for the system with electrical heat pump and absorption heat pump, respectively.

The article presents a numerical model of the concrete heat accumulator for solar heating systems. Model uses control volume finite element method with an explicit solution method for time integration. The use of an explicit method is an essential advantage in the simulation of time-dependent changes in temperature of the air at the accumulator inlet. The study compares the results of numerical model calculations of the accumulator heating with experimental measurements and with computational fluid dynamics modeling. The comparison shows a good correlation between the results of calculation using the model and the results of measurements.

The paper presents the calculations for the failure conditions of the ORC (organic Rankine cycle) cycle in the electrical power system. It analyses the possible reasons of breakdown, such as the electrical power loss or the automatic safety valve failure. The micro-CHP (combined heat and power) system should have maintenance-free configuration, which means that the user does not have to be acquainted with all the details of the ORC system operation. However, the system should always be equipped with the safety control systems allowing for the immediate turn off of the ORC cycle in case of any failure. In case of emergency, the control system should take over the safety tasks and protect the micro-CHP system from damaging. Although, the control systems are able to respond quickly to the CHP system equipped with the inertial systems, the negative effects of failure are unavoidable and always remain for some time. Moreover, the paper presents the results of calculations determining the inertia for the micro-CHP system of the circulating ORC pump, heat removal pump (cooling condenser) and the heat supply pump in failure conditions.

The paper presents the results of optimizing the coefficient of the share of cogeneration expressed by an empirical formula dedicated to designers, which will allow to determine the optimal value of the share of cogeneration in contemporary cogeneration systems with the thermal storages feeding the district heating systems. This formula bases on the algorithm of the choice of the optimal coefficient of the share of cogeneration in district heating systems with the thermal storage, taking into account additional benefits concerning the promotion of high-efficiency cogeneration and the decrease of the cost of CO2 emission thanks to cogeneration. The approach presented in this paper may be applicable both in combined heat and power (CHP) plants with back-pressure turbines and extraction-condensing turbines.

The article presents the results of surveys to assess the attractiveness of centralized heat supply systems in comparison with other heat sources. The heat source is an important element of the heat supply system which determines heating costs, comfort and environmental impact. The decision on the choice of the type of heat supply system is usually made by the investor or designer. Sometimes the equipment supplier or contractor has a part in this decision. The choice can be influenced by many different factors, also resulting from the specific location of the building. This is only partly determined by local law in the form of a local spatial development plan. the technical conditions (i.e. availability of heating or gas network), economic and financial, as well as much more subjective factors, such as the designer’s or contractor’s preference are also important. Aversion to district heating is growing, even when there are favorable conditions and the possibility of connecting the building to the heating network. Instead, a gas boiler or electrically powered heat pump is selected. This raises the question of whether such decisions are right and how they can be justified. As a research method, surveys were used, which were conducted among people who already have or will have an impact on design and investment decisions in the near future. The obtained results confirmed a large interest in district heating, appreciating their advantages in comparison with other methods of heat generation. The respondents also had the disadvantages that may lead to the use of an alternative methods of heat supplying in mind.

The paper presents the methodology of designing a system for accumulating waste heat from industrial processes. The research aimed to analyse the fluid’s movement in the heat accumulator to unify the temperature field in the volume of water constituting the heat buffer. Using the computer program Ansys Fluent, a series of computational fluid dynamics simulations of the process of charging the heat storage with water at 60°C, 70°C, and 80°C was carried out. The selected temperatures correspond to the temperature range of unmanaged waste heat. In the presented solution, heat storage is loaded with water from the cooling systems of industrial equipment to store excess heat and use it at a later time. The results of numerical calculations were used to analyse the velocity and temperature fields in the selected structure of the modular heat storage. A novelty in the presented solution is the use of smaller modular heat storage units that allow any configuration of the heat storage system. This solution makes it possible to create heat storage with the required heat capacity.

Recent dynamic changes in global fossil fuels markets and the European carbon dioxide emission allowances system have significantly impacted the energy sectors. These fluctuations also influence district heating (DH) markets where coal and natural gas remain dominant energy vectors in numerous European countries. District heating markets are distinct from other commodity markets due to their local nature and distribution requirements. Consequently, they can operate under various market models and have different price design policies depending on the country and region. With these considerations, this study aims to review and analyse the current market models and regulations of price formulation in the context of final prices in selected district heating markets. The primary objective is to conduct an in-depth analysis of the key district heating markets in Poland and compare the outcomes with the markets of neighbouring countries, including the Czech Republic, Slovakia, Lithuania, Latvia, Estonia, and Germany. Poland is taken as an example due to its high dependence on fossil fuels and its vulnerability to current global price fluctuations. The results indicate that Poland has one of the most regulated district heating markets, and these regulations can impact the profitability of district heating companies with high prices of fuel and carbon certificates observed in global markets. To create incentives for potential investors and incumbent companies to develop more sustainable and low-emission district heating markets in Poland – where energy transition processes are still underway – it is recommended to increase the frequency of formulation and approval of tariffs.

The numerical simulation of the heat transfer in the flow channels of the minichannel heat exchanger was carried out. The applied model was validated on the experimental stand of an air heat pump. The influence of louver heights was investigated in the range from 0 mm (plain fin) to 7 mm (maximum height). The set of simulations was prepared in Ansys CFX. The research was carried out in a range of air inlet velocities from 1 to 5 m/s. The values of the Reynolds number achieved in the experimental tests ranged from 93 to 486. The dimensionless factors, the Colburn factor and friction factor, were calculated to evaluate heat transfer and pressure loss, respectively. The effectiveness of each louver height was evaluated using the parameter that relates to the heat transfer and the pressure drop in the airflow. The highest value of effectiveness (1.53) was achieved by the louver height of 7 mm for the Reynolds number of around 290.

In order to provide sufficient cooling capacity for working and heading faces of the coal mine, chilled water is often transported a long distance along pipelines in deep mine, which inevitably results in its temperature rising owing to heat transfer through pipe wall and the friction heat for flow resistance. Through theoretical models for temperature increasing of the chilled water were built. It is pointed out that the temperature rising of the chilled water should be considered as a result of the synergy effects of the heat transfer and the friction heat, but theoretical analysis shows that within engineering permitting error range, the temperature increasing can be regarded as the sum caused by heat transfer and fraction heat respectively, and the calculation is simplified. The calculation analysis of the above two methods was made by taking two type of pipe whose diameters are De273 × 7 mm and De377 × 10 mm, with 15 km length in coal mine as an example, which shows that the error between the two methods is not over 0.04°C within the allowable error range. Aims at the commonly used chilled water diameter pipe, it is proposed that if the specific frictional head loss is limited between 100 Pa/m and 400 Pa/m, the proportion of the frictional temperature rising is about 24%~81% of the total, and it will increase with high flow velocity and the thin of the pipe. As a result, the friction temperature rising must not be ignored and should be paid enough attention in calculation of the chilled water temperature rising along pipe.

In order to select the most optimum parameters for running heat recuperation process from aerobic composting process, three testing stages were run involving the registration of the value of recuperated heat volume and the observation of cooling impact on composting process parameters. The values of thermal conductivity coefficient were measured as a function of compost temperature, density and age. The values ranged from 0.171 to 0.300 W/mK. The optimum parameters for process running were selected. Basing on them it was estimated how much heat will be possible to recuperate during the composting process on industrial scale using a battery of heat exchangers. For artificially aerated pile with the following dimensions: lower base 8 m, upper base 5 m, height 3.5 m, length 3 m; it will be possible to recuperate approximately 7.4 kW (from 1 m2 of heat exchanger surface - 774 W).

The paper presents the assumptions and methodology for investigating equivalent heat load testing of hot aircraft engine components. The basic heat loads occurring in an aircraft engine during aircraft flight are characterised. Diagrams of the proposed heat loads are presented, together with the number of cycles, and a test bench is characterised and shown to enable equivalent heat load testing of aircraft engine components.

This paper presents the methodology for determining thermal strains and stresses during heating the charge in a rotary furnace. The calculations were made with the original software, which uses the finite element method. The heat transfer boundary conditions used for computing were verified on the basis of industrial tests. Good compatibility between the experimental data and numerical calculations was obtained. The possibility of the material cracking occurrence was checked for a set exhaust gas temperature distribution on the furnace length. As a result, it was possible to develop steel heating curves characterized by short process times.

Thermodynamics deals with irreversible transformations of substances. Every thermodynamic property of a substance, as a function of two parameters describing its state, can be illustrated as a simply connected manifold. The term manifold stands for the Methods of Geometrical Representation of Thermodynamic Properties of Substances by Means of Surfaces. Generally, every transformation of a substance changes its energy (or enthalpy) by heat transfer and work done on it. All such changes (transformations) are considered to be irreversible and can be described using appropriate manifolds. Studies show that every transformation is associated with the degradation of energy. Such relations (between heat, work and other forms of energy or enthalpy) can be described by the Pfaff formulas and their integrations.

This article discusses the issue of irreversible energy degradation in heat transfer between two fluids. Irreversible heat transfer between separated fluids most often occurs through surface heat exchangers. All such processes are determined by convective heat transfer in thermal boundary layers and conduction through the wall. Consequently, entropy changes of fluids in heat and mass transfer can be observed in these layers. While the entropy rate of the heating fluid is negative and that of the heated medium is positive, the sum of entropy changes of all substances involved in the heat transfer process is always positive. These sums, known as entropy increase (entropy generation), can be interpreted as the measure of irreversible degradation of energy in heat transfer processes. The consequence of this degradation is that an arbitrary engine powered by the degraded (lower-temperature) heat flux will operate at a lower efficiency. The significance of this discussion relates especially to cases in power plants and cooling systems where surface heat exchangers are used. In the discussion proposed is the entropy increase as a criterion of irreversible energy degradation in heat transfer. Such introduced measure of effectiveness leads to an analysis of local overall heat transfer coefficient optimization on the cone-shaped manifold.

This article presents the current and future situation of heat consumption in the Republic of Kazakhstan. The predicted growth of thermal loads until 2030 is shown in the example of Karaganda city. Therefore, the task of creating and implementing automated heat points into the system of heat-supply complexes of cities of the Republic of Kazakhstan is relevant. The article considers the concept of measurement and processing of information in district heating supply systems based on variable cycles of the interrogation of parameters of heat supply at the heat points. As a result of the conducted research, a microcontroller SMART-system for the implementation of rational modes of heat supply used in the process of obtaining and processing information on heat-consumption parameters and making control decisions regarding variable cycles of heat-supply-parameter interrogation at heat points was developed and implemented. The results of the study have been successfully tested on the facilities equipped with automated heat points.

The purpose of this article was to discuss the use of adsorption chillers for waste heat recovery. The introduction discusses the need to undertake broader measures for the effective management of waste heat in the industry and discusses the benefits and technical problems related to heat recovery in industrial plants. In addition, heat sources for adsorption chillers and their application examples were described. The principle of operation of adsorption chillers is explained in the next chapter. Heat sources for adsorption chillers are indicated and their application examples are described. The above considerations have allowed the benefits and technical obstacles related to the use of adsorption chillers to be highlighted. The currently used adsorbents and adsorbates are discussed later in the article. The main part of the paper discusses the use of adsorption chillers for waste heat management in the glassworks. The calculations assumed the natural gas demand of 20.1 million m3 per year and the electricity demand of 20,000 MWh/year. As a result of conducted calculations, a 231 kW adsorption chiller, ensuring the annual cold production of 2,021 MWh, was selected. The economic analysis of the proposed solution has shown that the investment in the adsorption chiller supplied with waste heat from the heat recovery system will bring significant economic benefits after 10 years from its implementation, even with total investment costs of PLN 1,900,000. However, it was noted that in order to obtain satisfactory economic results the production must meet the demand while the cost of building a heat recovery system shall not exceed PLN 1 million.

The relevance of this study is explained by the growing interest in increasing heat transfer by the development of high-performance thermal systems. Increasing the thermal characteristics of heat-exchanger systems is necessary for the efficient use of an energy source. The purpose of this study is to review the existing methods of heat-transfer intensification and examine the mathematical model of such an increase in efficiency when using petal turbulators. This study is based on a high-quality, reliable combination of proven theoretical methods (analysis, synthesis, concretization, generalization, modelling), and empirical methods. It is the introduction of turbulators into the flow channel that is one of the best methods of increasing passive heat exchange through such advantages as ease of manufacture and operation in combination with low operating and production costs. This study contains both passive and active methods of heat-exchange intensification that have been extensively investigated over the past decade. For this purpose, the newest studies of mainly authors from other countries were used, their detailed analysis was conducted and the results were summed up. In addition, a mathematical model of increasing the thermal efficiency of convective heating surfaces in a bundle of smooth pipes using petal turbulators was investigated, the results of which were tested on an experimental installation. The paper may interest a circle of readers interested in the problem of improving the thermal characteristics of heat exchangers, including researchers, teachers and students of higher educational institutions in the field of heat-power engineering.

The paper presents analytical relationships based on the theory of Green’s functions. The relationships refer to instantaneous and continuous as well as point and ring heat sources which are discussed. The relationship relating to continuous ring source is the basis for modelling and designing of spiral ground heat exchangers. Heat transfer in the infinite and semi-infinite body was considered. In the latter case, the image method was discussed. Using the results of measurements regarding heat transfer in the ground with a heat exchanger in the form of a single coil installed, a comparison of calculated ground temperatures with measured values was presented.

Knowledge of the temperature distribution in subsurface layers of the ground is important in the design, modelling and exploitation of ground heat exchangers. In this work a mathematical model of heat transfer in the ground is presented. The model is based on the solution of the equation of transient heat transfer in a semi-infinite medium. In the boundary condition on the surface of the ground radiation fluxes (short- and long-wave), convective heat flux and evaporative heat flux are taken into account. Based on the developed model, calculations were carried out to determine the impact of climatic conditions and the physical properties of the ground on the parameters of the Carslaw-Jeager equation. Example results of calculated yearly courses of the daily average temperature of the surface of the ground and the amount of particular heat fluxes on the ground surface are presented. The compatibility of ground temperature measurements at different depths with the results obtained from the Carslaw–Jaeger equation is evaluated. It was found that the temperature distribution in the ground and its variability in time can be calculated with good accuracy.

Heat consumption and steel loss for scale determine the costs of a heating process. The heating rate influences both. This paper evaluates the heating rate of a long charge made of three various materials, depending on the changes of the furnace atmosphere on the rotary furnace circumference. Numerical computing was performed based on a formulated heat transfer model in the rotary furnace chamber, while considering the growth of the scale layer. One heating curve was selected, which has allowed the heating time to be reduced by 36% while limiting the scale loss by 40%. It was also shown that the thermal stresses and strains should not lead to fractures of the charge heated.

The inverse solution to the heat flux identification during the vertical plate cooling in air has been presented. The developed solution allowed to separate the energy absorbed by the chamber due to radiation from the convection heat losses to air. The uncertainty tests were carried out and the accuracy of the solution has been estimated at a level of 1%-5% depending on the boundary condition model. The inverse solution was obtained for the temperature measurements in the vertical plate. The stainless-steel plate was heated to 950°C and then cooled in the chamber in air only to about 30°C. The identified heat transfer coefficient was compared with the Churchill and Chu model. The solution has allowed to separate the radiation heat losses and to determine the Nusselt number values that stay in good agreement with the Churchill and Chu model for a nearly steady-state air flow for the plate temperature below 100°C.