Hot Water Supply System Research Articles

Varieties and technical characteristics of solar collectors

Background. Energy resource is one of the main components of a successful country. The possibility of using environmentally clean and affordable renewable energy and creating systems for taking solar radiation is a priority in ensuring the economic energyindependence of the state. At present, there are a variety of solar systems according to the technical solution and their use: thermo- and photovoltaic, systems with metal absorbers, solar stations for industrial or private electricity generation, for hot water supply, heating, air conditioning, and other technological needs. But questions about effective insolation and the choice of materials for these systems remainopen. Therefore, the development of efficient solar collectors (SC) with a rational choice of their geometric and thermophysical parametersis absolutely relevant.Objective.The purpose if the paper is to explore and develop efficient devices with maximum absorber throughput and minimization of heat loss.Methods. Analysis of developments of solar collectors by their shape and technical characteristics.Results. According to the review, new developments of solar collectors are marked by the originality and novelty of the technical solution. Corrugated pipe, cellular polycarbonate, activated carbon, a tangle of heat-conducting wire are usedas the absorber material,and the additional heat-accumulating coating – a solution of Glauber’s salt is applied. The inventions can be used in heating and hot water supply systems, indoor air heating, and in equipment that converts electromagnetic radiation from the sun into thermal energy for heating liquid coolants, as well as into electrical energy. For the maximum power of the collector, a receiving surface with a coating of high solarenergy capacity is used and thermal insulation is additionally installed to minimize heat loss. The authors of the article developed and patented a fundamentally new geometric spherical SC.Conclusions. The creation of new and improvement of existing SC ensures energy independence both in the private sector and nationwide, as well as to take care of the environment.The spherical shape allows you to use it effectively during the day.

Research of accidents pipelines

The durability and reliability of operation of steel pipelines of water supply and sewage systems is determined in particular by the quality of their welded joints, which in turn depends both on the composition of the materials used in their manufacture and on the observance of welding technology. The composition of impurities of transported liquids, which can cause corrosive destruction of materials, also has a significant impact on the reliability of pipeline systems. These phenomena are especially important in hot water supply and industrial drainage systems, where the destructive influence of physical factors and the chemical composition of the environment can be decisive. It was found that the loss of strength of the pipeline is caused in particular by improper operation, under the conditions of which micro-flaws of welded joints of pipelines appear, which leads to their destruction. The results of examinations and experimental studies of the strength of welds of steel process pipelines are presented. An external inspection was carried out, determination of the structure and strength parameters of pipeline welds, layer-by-layer analysis of corrosion damage on their inner surface. It was found that premature destruction of welded joints of hot water supply pipelines and industrial sewage is caused by long-term operation in a stressed state. Under such circumstances, the uneven coarse-grained structure of the seam, the presence of non-metallic inclusions in the metal structure, and violations of the welding technology had a critical impact on the loss of strength. In order to increase the corrosion-mechanical resistance of welded joints of industrial pipelines, it is necessary to modify the surfacing metal of the weld to break down the structure and significantly reduce non-metallic inclusions, as well as to improve the technology of manual arc welding with coated electrodes, in particular, the root layers of welding seams.

Study on the Energy Efficiency Improvement and Operation Optimization of a Solar Water Heating System

The solar-assisted electric boiler water heating systems adopted in student apartments at universities have some shortcomings, such as unsuitable system designs, unstable water supply temperature, and excessive power consumption. As discussed in this paper, the hot water supply system was reformed, and two apartments with the same building area, same solar collector area, and similar water consumption were selected to be used in comparative experiments. The auxiliary heat source for one of the apartments was changed from an electric boiler to three air source heat pumps, and a constant temperature water tank was added to form a double-tank water supply system. In addition, the operation strategy was adjusted. The other apartment was not modified. The energy consumption, solar fraction, water supply quality and economy of the two systems were analyzed and compared. The results showed that the transformation plan is reasonable and feasible. The solar fraction of the reformed system was significantly improved. The water supply temperature of the original system ranged from 35 °C to 60 °C, but it was shown to stabilize between 40 °C and 50 °C after the transformation. The average power saving rate of the reformed system reached 72.70%, and this economic benefit is highly significant. Additionally, the TRNSYS simulation software was used to model and optimize the control of the system.

The mineral composition of sediments and the reasons for their formation in the heating and hot water supply systems of the towns of Apatity and Kirovsk (the Murmansk Region)

The development of the housing and communal complex is focused on ensuring guaranteed access of the Russian population to high-quality drinking water. Due to the deterioration of drinking water quality, the mineral composition of sediments in the heating and hot water supply systems of the towns of Apatity and Kirovsk (the Murmansk region) has been studied. It has been established that sediments in the heating system mainly consist of iron oxides and oxyhydroxides: magnetite, goethite and lepidocrocite. All these mineral phases are products of active oxidation (corrosion) of steel pipes and heating system equipment. No mineral phases of ferrous forms of iron have been found in the sediment, which indicates sharply oxidizing environment in the heating system. The presence of sulfur-containing mineral phases, namely, anhydrous calcium sulfate - anhydrite and elemental sulfur, has been recorded in the heating system of the Apatity combined heat and power plant. Indirectly, the presence of such sulfur-containing phases may indicate the possible presence of microflora (bacteria) in the heat-transfer agent, in the metabolic processes of which sulfur and sulfur-containing compounds are involved.

The influence of snow deposits on thermal efficiency of vacuum tube collectors

Global warming promotes the acceleration forces all countries to reduce fossil energy sources and increase renewable energy sources with the development of environmentally friendly resource-saving technologies. The vast territory of Russia is permafrost or has seasonally frozen soils. The use of renewable energy sources, especially solar energy sources, is especially important for such territories.The article presents the experimental results of the operating modes of a pilot industrial solar hot water supply system with two vacuum tube collectors after snow pollution or icing of pipe surfaces. This technique is used to measure the hourly values of thermal energy from the conversion of solar radiation by collectors with polluted and cleaned collector surfaces on a sunny day after snowfall or icing. The average hourly value of solar insolation (with contaminated surfaces and after their cleaning) is obtained by integrating the meter recordings on the incident heat flux from the sun (by 600 values each) at an interval of 6 seconds. It is found that when the collector pipe surface is iced, the decrease in the thermal energy supply is maximum and amounts to 36.96 %. In other cases it varies from 8.51 to 13.47 %.

Icreasing the efficiency of district heating supply systems by local heat distribution station modernation

The PURPOSE of the study is to improve the efficiency of district heating systems. To achieve this purpose, the following tasks must be completed. To consider the problems of functioning of an open heat supply system functioning. Perform an analysis of technical solutions for the modernization of local heat distribution and metering station are presented. To develop a technological scheme of local heat distribution station with a hot-water supply system. To determine the main technical, economic and investment indicators of the developed technical solution.MATERIALS AND METHODS. Measurements were made using the local heat metering station. When solving the set tasks, a methodology for assessing efficiency was applied with the calculation of capital and operating costs, including the calculation of the payback period.RESULTS. A new scheme for regulating of hot water supply system recirculation with open connection of consumers to a centralized source is proposed. The results of the implementation of the developed technical solution of local heat distribution and metering station for apartment buildings in Yoshkar-Ola city are presented. An experimental study of the effect of a joint additional installation of a pump and a control valve on the hot water supply system recirculation line before the mixing unit for hot water recirculation with return pipe and before the direct-acting temperature controller was the first to do. As a result, the consumption of district water was reduced by 36 - 39%, the temperature in the return pipeline was reduced by 13.5%; the enthalpy of the hot water was reduced from 0.168 to 0.145 Gcal/m3, the required circulation in all risers of the hot water supply system was ensured.CONCLUSION. The use of the developed technical solution for the modernization of local heat distribution and metering station increases the efficiency of district heating supply systems. Calculations made on the basis of the readings of automatic custody heat transfer meter showed that the payback period for the technical solution is 40 days. The proposed solution is recommended for use in local heat distribution station of open heat supply system in order to reduce water rate, lower the temperature in the return pipeline and reduce heat losses, improve circulation in all riser pipes of the hot water system.

ОПЫТ ИСПОЛЬЗОВАНИЯ ГЕОТЕРМАЛЬНОЙ ЭНЕРГИИ ПРИПОВЕРХНОСТНОГО МАССИВА ДРЕВНИХ ГРАНИТОИДОВ ДЛЯ ЦЕЛЕЙ ТЕПЛОСНАБЖЕНИЯ (ЮГ ЗАПАДНОЙ СИБИРИ)

An example of transition of the heating- and hot-water supply system to a low-temperature geothermal energy source from the Paleozoic granitoid massif is given for a secondary school building in Novosibirsk. The necessity for change the source of heat supply arose in 2018 due to wear and tear of the coal boiler house old equipment, which has provided the school with heat since it was built in 1964. At the time of the geothermal project implementation, there were already several cases of successful use of underground heat-producing probes arranged in specially drilled geothermal wells for heating public facilities in neighboring Siberian cities (Tomsk, Barnaul). However, loose sedimentary rocks there served for the source of heat energy, that greatly simplified and accelerated the tasks implementation. The described experience of heating – and hot-water supply of building due to the low energy from a shallow lying massif of ancient rocky grounds with intrusive genesis is unique for Russia and can serve as a platform for the implementation of geothermal projects in regions with complicated ground conditions and moderately cold climate.

Improving the energy efficiency of operational services in the context of modernization of hot water supply systems in an apartment building

Improving the energy efficiency of operational services in the context of modernization of hot water supply systems in an apartment building

Research of water distribution in stratification heat accumulator of a solar heating system

The calculation method for a water distributor of a constant cross section uniformly perforated along the height for a multilayer stratified thermal storage tank used in solar heating and hot water supply systems was developed.

Improving the Efficiency and Reliability of the Internal Heating System on the Example of a Shopping Center

Shopping centers belong to the type of buildings in which all internal engineering systems are present. Therefore, the study of the shopping center, as an example of carrying out work on the application of various proposals for the use of secondary energy in the complex and, consequently, for energy saving and improving reliability and efficiency, is relevant. In addition, the use of various heat carriers allows us to consider the issue of energy saving more widely. The article compares the traditional heat supply system and the combined system, as well as the development of optimal energy-ecological solutions for the design of the heat supply system of a shopping center using the heat of condensation of refrigeration equipment used to comply with the technological process of cooking and storing food. The peculiarity of the proposed solution is that CO2 is used as a refrigerant in the refrigeration system, which is proposed to be used as a heat carrier for heating water in the hot water supply system.

Circulation management in hot water supply systems

The compliance of the actual heat consumption for heating cold water for public hot water supply service with the approved standard has been analyzed. Using passive engineering experiments, we studied the operating modes of hot water supply systems for several groups of houses, in which different methods for regulating water consumption in hot water supply systems were used. Data were collected using online energy monitoring and commercial metering system. Features of the static and dynamic load regulation of hot water systems have been investigated. The effect of methods for regulating the heat load of hot water supply systems on their actual heat consumption has been analyzed. An assessment has been made of the possibility of bringing the actual operating mode of the hot water systems to the specified value which is the basis for calculating the consumption rate. Ways to improve the efficiency of hot water supply systems have been determined. Conclusions have been drawn concerning the need to revise the standardized indicators of hot water quality and adjust the methodology for calculating the consumption rate in hot water supply systems.

Improving a heat supply system by increasing the efficiency of the heat pump unit

The reliability and efficiency of the operation of district heating systems is largely determined by the efficiency of preparation of heating network water. In open heat supply systems, make-up water, among other things, compensates for the water intake in hot water supply systems. A number of technologies have been developed that increase the efficiency of an open heat supply system by reducing the water consumption in the supply pipeline of the heating network, increasing the operating time of the heat pump, and increasing the specific generation of electricity for heat consumption at the CHP plant due to additional cooling of the network water in the return pipe of the heating network.

Applicable design of multi-functional cascade heat pump system for an office building

When the cascade heat pump system is applied as a multi-functional system that can be used not only for hot water supply but also for air-conditioning of buildings, the low-stage cycle is responsible for indoor heating and cooling thermal load, and the high-stage cycle is responsible for hot water supply by raising the refrigerant temperature. Unlike the existing cascade heat pump system designed with only one operation mode for hot water supply, the multi-functional cascade heat pump system should be considered with various parameters. This study was proposed a design sequence of the cascade heat pump system for building application, and the energy-saving performance was compared with the existing cascade heat pump system for hot water supply and parallel heat pump system for air-conditioning. The office building was set for the study, and the thermal load of the building was calculated in the TRNSYS program. The systems were calculated using the thermodynamic equation and the model built into EnergyPlus. As a result, the system can be affected by the outdoor air heat source. The energy-saving performance was 25% for the multi-functional cascade heat pump system compared to the simultaneous use of the existing system.

MODELING THE DYNAMICS OF THERMAL ENERGY ACCUMULATORS AS CONTROL OBJECTS

The article defines the relevance of research on options for using heat accumulators in the heat supply system of industrial premises. Typical technological schemes of liquid heat accumulators are considered and shortcomings of existing mathematical models are determined. The technological scheme of a capacitive type battery is selected and analyzed, as the most common in solar heating and hot water systems. It has been established that for a non-stationary process, the thermal inertia of the body reinforcement and thermal insulation cannot be neglected, therefore, the storage tank cannot be considered as a single-capacity object. Based on the analysis of the heat balance of structural elements of heat storage devices, a mathematical model of the dynamics of the accumulator tank as a two-capacity object with lumped parameters is formulated. The resulting simplified mathematical model makes it possible to identify the simulation object (a capacitive type water accumulator). In the considered embodiment, the heat accumulator is used in hot solar water supply systems for preheating water. For use in dual-circuit systems of solar heating and hot water supply, heliolectors with antifreeze are used, and water is heated in heat storage tanks using heat exchangers. The formulated mathematical model of a tank of a combined accumulator with a heat exchanger when used as a liquid heat carrier - antifreeze (to exclude icing of the system), in which, to simplify the model (reduce the order), the heat capacity of the tubes is related to the heat capacity of the heat carrier in the volume of the tubes, and the mass of the body to the mass of liquid in it . For the development and analysis of an automatic temperature control system, the obtained models are a system of nonlinear equations, the solution of which is advisable to carry out in computer environments.

Thermal analysis of water distillation system using pv/t collector combined single basin still

A simulation program combined with experiment for hot water supply system using PV/T collector combined with Single Basin solar still is introduced in this paper. PV/T collector is known as a thermal - electrical co-generation device. Besides the ability to generate electricity, it also generates heat to heat water, serving water distillation at night. This combination not only helps to increase the electrical capacity of the solar cells, but also helps to increase the total distillation output of the day and night for the Single Basin solar still. Based on the energy balance equations at the components of the PV/T collector, the hot water tank and the components of the Single Basin solar still, a simulation program is set up using the MATLAB programming language with the Simulink tool. The simulation results are verified experimentally with high accuracy from 4.24% to 7.11%. The article demonstrates that the electrical capacity of solar cells increased by 8.6%, the average electrical efficiency and average energy efficiency of PV/T collector reached 15.1% and 36.2%, respectively. Besides, the distilled water output in one day increased by an average of 38.2% compared to the traditional Single Basin water distillation equipment. The simulation program in this study can be applied in different weather conditions, saving time and money for the implementation of projects combining PV/T collector and Single Basin solar still for arid localities and remote islands.

Performance of Ground Source Heat Pump for Hot Water Supply Systems Using Open-type Underground Heat Exchanger

Performance of Ground Source Heat Pump for Hot Water Supply Systems Using Open-type Underground Heat Exchanger

Readiness of apartment building residents for hot water supply modernization in Ukraine

Kudinov I. О., Serheieva K. М., Klymenko A. О.Readiness of apartment building residents for hot watersupply modernization in Ukraine. – Article.Features of social and institutional readiness of residentsof apartment buildings (condominiums) for reforms ofcentralized hot water supply in Ukraine are analyzed.The paper represents results of social survey research ofresidents of apartment buildings in Zaporizhzhia (Ukraine).The methodological basis of the research is generallyscientific and special sociological methods of scientificcognition. The research determines socio-demographic andinstitutional characteristics of centralized hot water supplyservices consumers in Zaporizhzhia, the level of interest inthe preservation and modernization of centralized hot watersupply system in the city, the level of readiness of apartmentbuilding residents for collective responsibility for theconsumption of hot water supply services and strategies formodernization of the centralized hot water supply system.Research results identified possible ways to increaseapartment building residents’ readiness for modernization:1) development of the subjectivity of the apartmentbuilding residents, because it is impossible to solve commonproblems of such buildings in case of unity absence of theirinhabitants; 2) increasing the level of social interactionbetween the community and local authorities; 3) developinstitute of social organizers (social technicians). Researchresults suggest that condominium residents of Zaporizhzhiashow a very low level of awareness in the field of housinglegislation and the condition of their own buildings and thefact that every such resident understands the feasibility andneed to modernize the existing hot water supply system.The main obstacle to the modernization of hot water supplysystems is the need to attract large financial resources.The second – is the unwillingness of apartment buildingresidents to cooperate. One of the ways to solve the problemis to provide a quality information campaign to raise publicawareness of: financial capabilities for apartment buildings;better practices of project activities of OSBB buildings.

Proposal and preliminary experimental investigation on a novel efficient integrated system of combined refrigeration, heating, and hot water supply

Poly-generation systems with high integration can meet various needs of users. Therefore, design and efficient operation have always been the focus of attention. In this paper, a novel multi-functional system with R410A as the working fluid is proposed. Cooling, heat, and hot water can be provided under five kinds of operation modes. The most prominent advantages of the system lie in the high integration of multiple functions and high effectiveness in the combined cooling/hot water mode. The feasibility of system integration and mode switching is firstly analyzed and validated. The variation regulations of determining variables and performance indicator, including compressor inlet and outlet pressure, valve opening, and coefficient of performance, are revealed based on the self-built experiment rig. Research results exhibit that, an increase in the water tank temperature can promote the compressor outlet pressure. The average difference of inlet pressure between water tank temperatures of 50 °C and 40 °C is 30 kPa, while that of outlet pressure is 611 kPa. The larger the charge amount, the smaller the valve opening. Besides, under typical operating conditions, the total COP of the combined refrigeration/hot water mode can reach up to 8.25, and it is 51% more efficient than that of the hot water mode.

Перспективи використання електричних теплогенераторів у системах централізованого теплопостачання для надання допоміжних послуг енергосистемам

The projection of the hot water thermal load of the district heating system’s consumers is developed. It is shown that the total heat load of centralized hot water supply systems in Ukraine today is about 3.0 GW. It determines the full potential of maneuvering power of electric heat generators to provide ancillary services to a power system. Moreover, due to the decline of the Ukrainian population and the decrease of demand for thermal energy, it is expected to decline in the future and will reach 1.9 GW in 2050 (down 36.6% compared to 2020). During the non-heating period, under market conditions, it is expected that heat-generating technologies will compete with each other for the ability to supply heat water to the district systems. The solar collectors will be excluded from the market competition as they do not require a fuel, and therefore their use during the non-heating period is the most profitable. Another technology that will be in use is biomass boilers, their minimum reduced weighted average lossless price of thermal energy (Marginal Levelized Price of Energy - MLPOE) is 102 UAH / Gcal. Gas cogeneration technologies also have a great chance to use their thermal capacity (MLPOE - 258 UAH / Gcal), heat pumps (MLPOE - 155 UAH / Gcal), electric boilers (MLPOE - 633 UAH / Gcal) and gas boilers (MLPOE - 964 UAH / Gcal) will also be used. The analysis of different options for providing ancillary services to the power system showed that considering the competition among technologies, the most feasible option is to involve CHP equipped with electric heat generators. This option allows performing both daily regulation of power and load of power system and also regulation during the system’s night minimum load. At the same time, the balancing power for the current situation is about 1.3 GW for daily control and 1.4 GW for regulation during the night minimum load Keywords: structure of heat generation, heat-generating technologies, heat load, power system, schedule of electric loads, night failure, power, heat pumps, electric boilers, CHP

Оцінка видобувного потенціалу державного сектору вугільної промисловості України

The projection of the hot water thermal load of the district heating system’s consumers is developed. It is shown that the total heat load of centralized hot water supply systems in Ukraine today is about 3.0 GW. It determines the full potential of maneuvering power of electric heat generators to provide ancillary services to a power system. Moreover, due to the decline of the Ukrainian population and the decrease of demand for thermal energy, it is expected to decline in the future and will reach 1.9 GW in 2050 (down 36.6% compared to 2020). During the non-heating period, under market conditions, it is expected that heat-generating technologies will compete with each other for the ability to supply heat water to the district systems. The solar collectors will be excluded from the market competition as they do not require a fuel, and therefore their use during the non-heating period is the most profitable. Another technology that will be in use is biomass boilers, their minimum reduced weighted average lossless price of thermal energy (Marginal Levelized Price of Energy - MLPOE) is 102 UAH / Gcal. Gas cogeneration technologies also have a great chance to use their thermal capacity (MLPOE - 258 UAH / Gcal), heat pumps (MLPOE - 155 UAH / Gcal), electric boilers (MLPOE - 633 UAH / Gcal) and gas boilers (MLPOE - 964 UAH / Gcal) will also be used. The analysis of different options for providing ancillary services to the power system showed that considering the competition among technologies, the most feasible option is to involve CHP equipped with electric heat generators. This option allows performing both daily regulation of power and load of power system and also regulation during the system’s night minimum load. At the same time, the balancing power for the current situation is about 1.3 GW for daily control and 1.4 GW for regulation during the night minimum load Keywords: coal industry, production technologies, modernization, forecast, development