Hot Water Heating System Research Articles

Investigation of the Temperature Distribution and Energy Consumption of an Integrated Carbon Fiber Paper-Embedded Electric-Heated Floor

This study examined spatial and temporal thermal performance and energy consumption. The temperature distribution in the running period was monitored in test rooms with integrated electric- and hot water-heated floors. The short- and long-term energy consumption of the two heating systems were recorded and compared. The results indicated that the integrated electric heating system generated higher temperatures for indoor air and on the exterior surface of the wooden floor than the hot water heating system; meanwhile, the difference in the mean temperatures of the exterior and rear surfaces of the electric-heated floor was 2.44 °C, while that of the hot water-heated test room was 13.25 °C. The efficient structure of the integrated electric heating system saved 22.97% energy compared to the hot water system after short-term (7 h) charging and reaching a dynamic balance, and it efficiently increased the energy utilization rate to 11.81%. After long-term charging, the daily energy consumption of the integrated electric heating system consumed much less energy than the hot water system every month. The integrated electric heating system saved 62.55% and 34.30% of energy in May and January, respectively, and consumed less than half of the energy the hot water system consumed in the less cold months. Therefore, a high-efficiency and energy-saving integrated electric-heated floor could be a potential indoor heating solution.

ТЕХНИКО-ЭКОНОМИЧЕСКОЕ ОБОСНОВАНИЕ УСТАНОВКИ СОЛНЕЧНЫХ КОЛЛЕКТОРОВ ДЛЯ ИНДИВИДУАЛЬНЫХ ДОМОВ

The hot water supply system of Perm uses solar energy. The aim of the study was to substantiate the economic efficiency of solar collectors and determine their payback period taking into account climatic conditions, equipment cost and economic criteria. The proposed technical solutions of solar energy using were analyzed and compared with electric heating. During the study, the authors defined the required minimum solar collector area for a household (taking into account the hot water standard for Perm) as a functional dependence of the amount of incoming solar insolation on the amount of using heat energy. We evaluated domestic and imported solar collectors on the required parameters. The value of the reduction in the payment for electric energy was taken as the income for the households. The economic efficiency was calculated based on the forecasted average electricity tariff, taking into account inflation from 2 to 16 %. The payback of a solar hot water heating system depends primarily on the cost of purchase, installation of equipment and on the discount rate. The practical significance is to substantiate the economic efficiency of solar collectors for consumers. The methodology and results of the study can be used in private residential construction and in justification of the use of alternative energy sources for Russian regions with low insolation.

Artificial neural network model for predicting CO2 heat pump behaviour in domestic hot water and space heating systems

The natural refrigerant, CO2, possesses thermophysical properties that make it highly suitable for domestic hot water (DHW) production using heat pump technology. In this study, the development and validation of an artificial neural network (ANN) model that enables efficient design and control of a CO2 heat pump is presented. The study employs experimental data from a CO2 heat pump with a nominal heat capacity of 8 kW. The fully instrumented rig includes the heat pump and a pump rig designed to generate system temperatures representative of various space heat and DHW demands. A comprehensive dataset was generated through systematic variation of inlet temperatures and setpoints. The ANN provides predictions for outlet temperatures, heat production, and electricity consumption utilizing inlet flow rates, temperatures, and setpoints as inputs. These predictions are important for condition monitoring or in a smart operation management framework that determines optimal schedules for the machine.

Data-driven predictive control for demand side management: Theoretical and experimental results

Demand side management is perceived as a tool to support a secure and reliable energy system operation amid growing integration of renewable energy resources. However, the lack of scalable modeling and control procedures hinders the practical implementation. To address this challenge, this paper proposes a novel signal matrix model predictive control algorithm. Compared to existing data-driven methods, this approach explicitly provides stochastic predictions considering both disturbance and measurement errors with few tuning parameters, ensuring reliability by high-probability constraint satisfaction. The performance is extensively compared with three state-of-the-art algorithms in a space heating case study using a high-fidelity simulator. The results are further validated with physical experiments using the same system that the simulator is based on. To assess transferability, the algorithm is further implemented on diverse controlled systems, including a domestic hot water heating system and a stationary electric battery. The simulation results show that, compared to existing data-driven methods, the proposed approach improves constraint satisfaction and energy savings by up to 90 % and 8 %, respectively. The experimental results further confirm that the algorithm is applicable to multiple tasks of demand side management, with reasonable control performance observed in all case studies.

Teaching differential equations through modelling: hot water heater

We present an example of one of the modelling projects we assign to students in our differential equations classes. Students are asked to determine how to run a cost-efficient hot water heating system. We consider a cylindrical tank filled with water and heated by a heating element immersed in it. Together with students we discuss physical laws governing the process and make assumptions necessary to build a model. One of the goals of the modelling activity is to compute the time needed for water to reach the desired temperature given the power of the heating element and the size of the water tank. Several different scenarios can be discussed. Assuming the cost of heating the water is directly related to the time for which the power is ON, students can choose the most cost-efficient scenario. We provide the description of several modelling activities and obtained results.

Priorities in Croatian School Building Maintenance: A Comparison of the Main Stakeholders’ Views

This paper aims to examine the opinions of the main recognized stakeholders in the maintenance of school buildings (i.e., the construction experts within the founders’ organization, the school staff, and the students), compare their views on the maintenance priorities, and identify certain differences. These data provide information about user needs, can help school founders make maintenance decisions, and are the basis for developing a new, balanced system of maintenance priorities. In the research, the survey questionnaire method was used to collect the data, whereby three groups of stakeholders evaluated the priority of eliminating certain defects in school buildings on a 5-point scale. For the purposes of the questionnaire, a model of 32 defects of the school buildings was created. In the questionnaire, 76 experts, 338 school staff, and 297 students participated. The research is limited to the Republic of Croatia. By conducting non-parametric statistical tests (Kruskal–Wallis and Mann–Whitney), it was shown that there were statistically significant differences in the stakeholders’ attitudes towards most maintenance priorities. There were also defects where statistically significant differences were not recognized, namely, regarding faulty lighting fixtures, faulty toilets, faulty sinks, faulty space cooling systems, faulty space heating systems, and faulty hot water heating systems. According to the experts, it is most urgent to remove faulty electrical installations, while according to the school staff, the highest priority is faulty sewage installations. The students believe that the priority is faulty toilets. The lowest priority is removing damage to the external environment (experts) and the facade (school staff and students).

ЭКОНОМИЧЕСКИЙ АСПЕКТ ДИАГНОСТИКИ НАКИПЕОБРАЗУЮЩИХ СЛОЕВ В ПЛАСТИНЧАТЫХ ТЕПЛООБМЕННИКАХ

The reliability and efficiency component of the 3rd generation heat and power network is characterized by the use of heat exchange devices, namely the plate type. Its main function is to heat the coolant for the needs of hot water supply and heating systems. However, the peculiarities of the chemical composition of the heat carrier cause contamination of heat exchangers in the form of scale layers on the heating surfaces. The process of scale formation on the plates of heat exchangers is one of the key factors affecting the failure of equipment and an increase in the energy intensity of heat distribution points, which leads to a decrease in the quality of services provided and an increase in financial costs in the field of heat supply. In the course of the study, by summarizing the known data, a sequence is formed for calculating the transport costs for the operation of plate heat exchangers under various conditions of scale formation. At the same time, the influence of scale thickness on the total cost of pumping one square meter of coolant is taken into account. This allows comparing transportation costs and the cost of removing scale from heating surfaces (according to the accepted cleaning method) depending on the thickness of the salt-forming layer and cleaning periods. The results of the study confirm the feasibility of regular monitoring of the thickness of salt-forming layers in plate heat exchangers to reduce operating costs for pumping the coolant.

Modeling and Simulation of Indirect Collector Solar Hot Water Heating System Based on TRNSYS

The use of solar energy is one of the important ways of clean energy heating in rural areas in the north, and the collector solar water heating system is an effective way to use solar energy. This paper takes a typical single residential house in a rural area of Shenyang as a research case to design an indirect collector solar hot water heating system. Based on the meteorological data of the winter heating period (November 1 - March 31 of the following year) in Shenyang, TRNSYS software was used to research the heat collection efficiency and scheme design of the heating system. The research results showed that: 1) The best material of the heat exchange coil of the hot water storage tank in the solar water heating system of the indirect collector is stainless steel with a thickness of 0.8mm; 2) The optimal installation angle of solar collectors in Shenyang is 55°; 3) The optimal area of the heat exchanger coil in the hot water storage tank is 4.40m2.

Economic features of services and energy cost for engineering systems

There are the results of some municipal services actual specific cost for residential apartment building. These services consist of cold water supply system; drainage and sewage systems; electricity; collection and disposal of municipal solid waste system. Authors did not indicate the specific operating cost for hot water supply and heating systems because their cost was constant. Research period: from 1st quarter of 2018 year to the 2nd quarter of 2022 year. This period was acute phase of Covid-19 pandemic period. Authors have written the dynamics changes in the cost of considered services. Researchers have presented additional factors which affect to the unit cost of municipal services in this paper. There is a brief overview of management companies types which could be in municipal service system. Also it has been considered their capabilities and limitations in creating tariffs process. Authors have identified different trends in the engineering service unit cost changing process. This article could be interested for management companies and tariffs planning departments of public municipal service system in different parts of Russian Federation. Results which were presented in this paper could be used in predictive mathematical models of municipal services economical parts in critical as pandemic or other emergency situations.

Techno-economic assessment of solar assisted precinct level heating systems with seasonal heat storage for Australian cities

District or precinct level heating systems are a promising way to incorporate solar for decarbonising the building heating sector. Despite growing interest in these technologies in Europe and China, there are no large-scale district heating systems in Australia. This study shows that a combined solar heat driven Domestic Hot Water (DHW) and Space Heating (SH) system with seasonal storage is technically and economically feasible for major Australian cities. A precinct scale solar-assisted domestic hot water and space heating system with seasonal heat storage has been designed and evaluated for Australian conditions. Technical performance was evaluated using solar fraction, storage efficiency and heat collection efficiency parameters. Economic performance was evaluated using the Levelized Cost of Heat for solar thermal (LCOHst) and whole system Levelized Cost of Heat (LCOH) with a combination of component cost data from China and Europe and energy cost data from Australia. A parametric study to identify optimal collector area and storage volume sizes shows that the proposed system could achieve technical and economic targets in all five Australian cities considered. The lowest LCOHst is 0.0597 USD/kWh in Hobart. Sydney and Perth could use nearly 100% solar energy to cover the heating demand with the proposed design.

CuS Nanoparticle-Based Microcapsules for Solar-Induced Phase-Change Energy Storage

Phase-change microcapsules with photothermal conversion capabilities have been the focus of research in the energy storage field. In this study, a route is developed to prepare photothermal conversion and phase-change energy storage microcapsules by copper sulfide-stabilized Pickering emulsion with dodecanol tetradecyl ester as the phase-change material (PCM) and melamine formaldehyde resin (MF) as a shell. Spherical CuS particles with a diameter of approximately 10 nm are first synthesized by a facile hydrothermal reaction. The obtained CuS nanoparticles are used not only as a stabilizer but also as a photothermal conversion material in the preparation of the microcapsules. Then, the PCM microcapsules are prepared by a one-pot interfacial polymerization route and showed a well-defined core–shell structure with an average size of approximately 7 μm. The synthesized microcapsules have a latent heat of up to 180.3 J/g and an encapsulation efficiency of 81.36%. Meanwhile, the thermal conductivity of the microcapsules increased by 115–254% compared to the core material due to the hybrid shell filled with CuS nanoparticles. The photothermal conversion capacity of the synthesized microcapsules is measured and calculated to be up to 85.6%, achieving light-induced phase change and further inducing the passive thermal cycle. This study provides a potential candidate for the application of light-induced energy storage microcapsules in fabric insulation, solar hot water heating systems, and solar thermal power systems.

Measures for Assessing the Effectiveness of Investments for Electricity and Heat Generation from the Hybrid Cooperation of a Photovoltaic Installation with a Heat Pump on the Example of a Household

In recent years, one of the key postulates in the European Union’s policy has become the development of renewable energy sources. In order to achieve the desired synergy effect, the idea of combining two selected sources of energy appeared. This article presents a technical and economic analysis of a hybrid connection of a ground source heat pump with a photovoltaic installation. Taking into account the heat demand of the building, a ground heat pump with a catalog nominal heating power of 25 kW was selected. This article presents the problem of the economic profitability of using a hybrid combination of a heat pump and photovoltaic panels in domestic hot water and central heating systems. The justification for the use of such heat sources in these installations is due to global trends and the gradual departure from conventional energy sources such as oil or gas boilers. This paper presents the economic and ecological results of using the pump heat connected together with photovoltaic panels. In the economic analysis, with the assumed installation costs related to the use of the considered heat pump and PV, two parameters commonly used in the investment analysis (static and dynamic) were used, namely, the simple payback period and the net present value of the investment. For the adopted assumptions, the usable area of the facility and the number of years of use were indicated, at which the investment in question is competitive with other alternative investment interest methods and will start to bring tangible benefits. The performed analysis also has measurable environmental benefits in the form of a reduction in carbon dioxide emissions at the level of 2893 kg/year into the atmosphere. The presented solution will help future investors understand the investment profitability mechanism for their households.

Parametric sweep simulation for greenhouse temperature field optimization: An Italian case study

The increasing importance of protected cultures in the last decades has led to the definition of aims for greenhouse design and functioning, in order to conjugate productivity and environmental sustainability. In particular, the optimization of greenhouses is finalized to better solar radiation adsorption and ensure to the crops a homogeneous temperature field for the whole growth time. An Italian case study is presented in this paper: the studied farm needs to project greenhouse geometry and design a hot-water pipes heating system to cultivate basil during the winter season, improving the exploitation of natural resources. A simulative analysis has been carried out by mean of COMSOL Multiphysics software, investigating the effects of greenhouse height, number of pipes and water temperature of the heating system on the inside temperature field through a parametric sweep approach. Twenty-seven scenarios have been simulated and three of them have been considered suitable for the farm applications. The simulative approach allows to collect data about the minimum number of pipes, the sensitivity of the internal temperature field to the outside temperature fluctuation (referred also to the height of the greenhouse) and the more suitable heating water temperature needed to ensure the required habitat to the basil crops, minimizing also temperature fluctuations.

Research on the influence of different heating strategies on energy consumption and carbon emission of a teaching building in Urumqi

In this paper, a typical teaching building of a university in Urumqi, Xinjiang was taken as the research object. Based on the existing maintenance structure, DesignBuilder software was used to explore the differences in energy consumption and carbon emissions generated by ordinary hot water heating system, ground thermal radiation heating and electric heating under different ventilation times. The effects of intermittent heating and continuous heating on heating energy consumption and carbon emission were studied by software simulation. Conclusion On the condition of ensuring indoor thermal comfort, electric heating is suitable for teaching buildings in Urumqi city, and intermittent heating is not suitable, continuous heating should be used. The heating system with the highest indoor comfort level is the ground heat radiation heating system, and the carbon emission is the ordinary hot water heating system. When the ratio of window and wall area under electric heating increases by 5%, the total heating energy consumption and carbon emission of buildings will increase by 10.8%–16.2% in the heating season, and the heating heat load of buildings will increase by 6.4%–8.2%.

An outbreak of Legionnaires’ disease in newborns in Serbia

ABSTRACT Legionnaires’ disease is an atypical pneumonia caused by inhaling small droplets of water containing the bacterium Legionella spp. In newborns, it is a rare event, usually associated with water births and the use of air conditioning systems or air humidifiers. A nosocomial outbreak of Legionnaires’ disease in the maternity ward of a secondary-care hospital in Arandjelovac, Serbia is described. Two male newborns were found to be infected with Legionnella pneumophila. On Days 7 and 6 of life, respectively, they were transferred to a tertiary-care hospital with signs of severe pneumonia which was radiologically confirmed. L. pneumophila was detected in tracheal secretions from both infants by RT-PCR, and its antigens were also positive in urine samples. The source of infection in the secondary-care hospital was the internal hot water heating system, and the main contributory factor to the emergence of the infection was the low temperature of the hot water which did not kill the bacteria during the available exposure time. These two cases highlight the importance of being cautious about possible Legionnaires’ disease in maternity wards with outdated or irregularly maintained internal water supply systems. The adoption of official guidelines for the control and regular maintenance of water supply systems, including the multidisciplinary cooperation of all relevant parties, forms the basis for direct monitoring for Legionella and the prevention of new outbreaks. Abbreviations: BCYE: buffered charcoal yeast extract agar; GVPC: glycine vancomycin polymyxin cycloheximide agar; LD - Legionnaires’ disease; TR-PCR: Reverse transcription polymerase chain reaction

Performance analysis of a prototype solar photovoltaic/wickless heat pipe embedded aluminum curtain wall-heat pump water heating system

In this study, a novel glazed photovoltaic heat pipe based curtain wall (PV-HPCW) heat pump system composes of the wickless heat pipe embedded aluminum veneer curtain wall as solar thermal collecting system and heat pump water heating system is proposed. This system assists in heat redistribution on the outer wall of the room to increase solar collection rather than transmission, and in which the collected heat is then transferred to the cold feed of the domestic hot water heating system. A dynamic model is developed to analyze the energy conversion and heat transfer process in the entire system by utilizing the energy balance approach to understand inter-connection and definition of the sorted equations. An experiment is executed and tested under the real outdoor weather conditions in Hong Kong, which is done by measuring the operational parameters, such as solar radiation, PV power generation, temperature at various points and compressor consumption. The simulation results reflect good consistency with the observation data, and indicating that the established model has reasonable accuracy to predict system performance. In outdoor condition, the results indicate that the average electrical and thermal efficiency of PV-HPCW module are around 9.44% and 20.22%, respectively; Similarly, the overall thermal efficiency and overall electrical efficiency (exergy) of the system are 44.6% and 12.8%, respectively; whilst the mean coefficient of performance, COP and the comprehensive coefficient of performance, COPpvt of the system are 3.64 and 5.12 respectively. The PV-HPCW heat pump system has a significant potential and benefits relating to solar heat and electricity. Thus, this innovative PVT technology based building envelop could be a promising building energy supply system with the advantage of proper resource utilization and compact structure, and all these positive implication would encourage the development of such high performance technology, which will contribute to the reduction of carbon emissions in the building sector and ultimately to reduce the urban heat island effect.

Thermal Loss Analysis of a Flat Plate Solar Collector Using Numerical Simulation

In this paper, we studied theoretically and numerically heated losses of a flat solar collector to model the solar water heating system for the Kazakhstan climate condition. For different climatic zones with a growing cost for energy or lack of central heating systems, promising is to find ways to improve the energy efficiency of the solar system. The mathematical model (based on ordinary differential equation) simulated the solar system work process under different conditions. To bridge the modeling and real values results, we studied the important physical parameters such as loss coefficient, Nu, Ra, and Pr values. They impacted the efficiency of flat solar collectors and heat losses of the system. The developed mathematical models, the design and composition of the software and hardware complex, and automated control and monitoring systems allow solar hot water heating systems to increase the energy efficiency of life support systems and heat supply of buildings by reducing energy consumption for heat supply. The simulation result showed that during the daytime, the temperature of water in the collector is 70°C; the storage of heated water since heated water is cooled at night. We defined that a work period of the system can be extended with high efficiency (April–October) for Almaty region.

Thermal Characterization of Medium-Temperature Phase Change Materials (PCMs) for Thermal Energy Storage Using the T-History Method.

To reduce energy consumption and increase energy efficiency in the building sector, thermal energy storage with phase change materials (PCMs) is used. The knowledge of the thermophysical properties and the characteristics of PCMs (like their enthalpy changes and the distribution of stored energy over a specified temperature range) is essential for proper selection of the PCM and optimal design of the latent thermal energy store (LHTES). This paper presents experimental tests of the thermophysical properties of three medium-temperature PCMs: OM65, OM55, RT55, which can be used in domestic hot water installations and heating systems. Self-made test chambers with temperature control using Peltier cells were used to perform measurements according to the T-history method. In this way the temperature range of the phase transition, latent heat, specific heat capacity, enthalpy and the distributions of stored energy of the three PCMs were determined. The paper also presents measurements of the thermal conductivity of these PCMs in liquid and solid state using a self-made pipe Poensgen apparatus. The presented experimental tests results are in good agreement with the manufacturers’ data and the results of other researchers obtained with the use of specialized instruments. The presented research results are intended to help designers in the selection of the right PCM for the future LHTES co-working with renewable energy systems, waste heat recovery systems and building heating systems.

The high performance of diethylhydroxylamine in comparison with hydrazine for the removal of dissolved oxygen from boilers of power plant

In boilers and hot water heating systems, hydrazine is used as one of the powerful reducing agents for eliminating oxygen. Due to the toxicity and carcinogenicity of this material, a suitable replacement named diethylhydroxylamine (DEHA) can be used. DEHA has low acute toxicity and animal tests do not show mutagenic activity. In this study, hydrazine and DEHA as deoxygenation materials were used in boilers of Tarasht power plant in Iran (Tehran). In different months (May to November), deoxygenation was examined by these two substances. The oxygen removal value of DEHA was equal to hydrazine and sometimes far better than it. The rate of deoxygenation reaction of DEHA was 40 ppb in most months of the year, but the number of peaks in hydrazine was greater (2 peaks with 50 ppb and 1 peak with 60 ppb). Hydrazine analysis is time-consuming, as well as pollutes the environment. On the other hand, DEHA of tests were completed sooner. Also, DEHA as an economical material with low toxicity can be a good alternative to hydrazine in boilers. This material can prevent boiler corrosion by oxygen removal.

Cost and environmental performance of forced air and hot water heating systems in post-Soviet countries

PurposeThe aim of the present study is to assess the selected heating systems (furnace and boiler) commonly used in the dwellings of seven post-USSR (the Union of Soviet Socialist Republics) countries. The systems were assessed in terms of their cost and environmental performance, with natural gas and electricity used as the main source of energy.Design/methodology/approachThe cost-effectiveness and environmental performance of the selected heating systems that have been commonly used in the selected post-USSR countries was assessed. Current energy (natural gas and electricity) prices that are applied in those countries were used.FindingsResults show that the furnace is the cheapest option, while natural gas is the cheapest source of energy, despite its high price in Tajikistan and Kyrgyzstan. Both heating systems could be considered eco-friendly options, although their efficiencies need to be considered at the design stage. Turkmenistan, Uzbekistan and Kazakhstan, which are the top natural gas producers, offer natural gas for the selected heating systems as both cost-effective and eco-friendly options.Practical implicationsA considerable reduction in electricity consumption and less harm to our environment can be achieved through the systems used in residential buildings in the region.Originality/valueThe outcomes of the present study offer value (in terms of cost-effective and eco-friendly options) for the end-users in the region.