Heating Installations Research Articles

Performance study of solar air collector-air source heat pump system inside the greenhouse

During the process of heating greenhouses, the phenomenon of inadequate heating installations is widespread. To address this issue, this paper proposed a solar air collector-air source heat pump (SAC-ASHP) system for greenhouses, combining solar technology with heat pump (HP) technology to provide sufficient heat during continuous cloudy days and winter. The heating capacities of the system on sunny, cloudy, and overcast days were 100.2 kWh, 112.3 kWh, and 157.8 kWh, respectively. The corresponding power was 30.1 kWh, 36.1 kWh, and 53.6 kWh. The coefficient of performance (COP) of the single air source heat pump (ASHP) for these days was 3.4, 3.2, and 3.0, respectively, while the COP of the solar heat pump (SHP) was 4.0, 3.5, and 3.1. Additionally, greenhouse employed heat and moisture recovery for humid air, aiming to provide a suitable environment for plant growth around the clock while conserving energy. The heat collection in the heat and moisture recovery combined HP mode was 66.7 % higher than in the heat exchanger (HE)-fan mode. This experimental study investigated the operational performance of the system in dynamic environments, revealing the stability of the system for greenhouse heating in cold regions, and providing new research ideas for greenhouse heating.

Advancing noise reduction strategies for domestic air-source heat pumps

With the increasing adoption of heat pump technology in the energy sector, addressing noise emissions is crucial for public acceptance, regulatory compliance, and sustainable urban planning. Air-Source Heat Pump's noise emission, noise sources, reduction strategies, problematic frequency ranges, and noise transmission within buildings are considered. Various noise reduction strategies, including the strategic siting, enclosures, and vibration isolation techniques, are discussed. This study considered a scenario of heat pump noise emission which generated noise complaints. The heat pump noise source is investigated though 24 hour monitoring of far field acoustics in a suburban residence. A commercial implementation of ISO 9613 is used to predict the environmental noise impact. Results demonstrated that levels exceeded natural background by as much as 10-15 dB but that this could be mitigated through strategic placement of the heat pump. This study underscores the importance of implementing comprehensive noise control strategies for Air-Source Heat Pumps in urban areas to safeguard community well-being and ensure regulatory compliance. By integrating innovative noise reduction technologies and considering factors such as strategic location of Air-Source Heat Pump, installation practices, building design, and proper urban planning policies can enhance Air-Source Heat Pump's reliability while promoting a sustainable urban development.

HEAT PUMP SYSTEM OF AUTONOMOUS HEAT SUPPLY FOR HEATING LOW-POTENTIAL COOLANT

Heat supply using a heat pump belongs to the field of energy-saving, environmentally friendly technologies and is becoming increasingly widespread in the world. This technology, according to the conclusion of a number of authoritative international organizations, along with other energy-saving technologies (use of solar, wind energy, ocean energy, etc.), belongs to the technologies of the 21st century. The main heat costs for household needs in buildings during the cold season are heating costs. This is explained by the operating conditions of buildings during the cold season, when heat loss through the building envelope significantly exceeds internal heat release. Therefore, to maintain the required internal air temperature, buildings are equipped with heating units. During the cold season, to create and maintain thermal comfort in buildings, technically advanced and reliable heating installations are required. The use of the proposed heat pump system will improve the efficiency of autonomous heat supply to decentralized and remote residential and industrial facilities, service enterprises. In addition, the proposed combination of heat pump units and renewable energy sources expands the resource base of the heat pump heating supply system, making it less dependent on fluctuations in ambient temperature, which is very important for increasing the level of reliability of heat pumps.

The Production of Porous Asphalt Mixtures with Damping Noise Reduction and Self-Healing Properties through the Addition of Rubber Granules and Steel Wool Fibers.

Conventional asphalt roads are noisy. Currently, there are two main types of mainstream noise-reducing pavements: pore acoustic absorption and damping noise reduction. However, a single noise reduction method has limited noise reduction capability, and porous noise-reducing pavements have a shorter service life. Therefore, this paper aimed to improve the noise-damping performance of porous asphalt mixture by adding rubber granules and extending its service life using electromagnetic induction heating self-healing technology. Porosity and permeability coefficient test, Cantabro test, immersion Marshall stability test, freeze-thaw splitting test, a low-temperature three-point bending experiment, and Hamburg wheel-tracking test were conducted to investigate the pavement performance and water permeability coefficients of the mixtures. A tire drop test and the standing-wave tube method were conducted to explore their noise reduction performance. Induction heating installation was carried out to study the heating rate and healing performance. The results indicated that the road performance of the porous asphalt mixture tends to reduce with an increasing dosage of rubber granules. The road performance is not up to the required standard when the dosage of rubber granules reaches 3%. The mixture's performance of damping and noise tends to increase with the increase of rubber granule dosage. Asphalt mixtures with different rubber granule dosages have different noise absorption properties, and the mixture with 2% rubber granules has the best overall performance (a vibration attenuation coefficient of 7.752 and an average absorption factor of 0.457). The optimum healing temperature of the porous asphalt mixture containing rubber granules and steel wool fibers is 120 °C and the healing rate is 74.8% at a 2% rubber granule dosage. This paper provides valuable insights for improving the noise reduction performance and service life of porous asphalt pavements while meeting road performance standards.

ЦИФРОВА СИСТЕМА КЕРУВАННЯ РЕЗОНАНСНОГО ІНВЕРТОРА НАПРУГИ З САМОЗБУДЖЕННЯМ

Phase-locked loop systems (PLL) are widely used in control circuits of transistor resonant voltage inverters of induction heating installations. One of disadvantages of PLL systems is low speed, which is caused by the presence of a low-pass filter. This disadvantage is absent in self-oscillating systems, when the switching moment of the transistors is determined on each of half periods. At the same time, an asymmetry of half periods is possible, which is a significant disadvantage if there is a transformer at the output of the inverter. A self-oscillating digital control system for a resonant voltage inverter and equal half periods durations of the inverter output voltage has been developed. It can work with different methods of regulating the output current and allows to provide switching modes of transistors with minimal power losses. References 7, figures 5.

More than floors and domes – contexts around ovens in the late neolithic of the Central Balkans

Even though ovens are the most prominent feature in the Vinča culture houses, they have often been neglected in the archaeological publications. Usually, only the information about their location or number of floors is provided, but more detailed descriptions are missing. This is also influenced by their poor preservation in the archaeological record, as parts of their upper structure are often missing. But, although fully preserved ovens represent quite a rarity, contexts surrounding them are usually filled with different categories of artefacts and architectural features. These complex contexts that include ovens, offer plethora of information about different socio-economic phenomena in the Late Neolithic of the Central Balkans. Therefore, ovens should be perceived as more than just fire installations for food processing and house heating, as they can offer insight into household organization and symbolic aspects of the Neolithic life. Additionally, ovens located in the outdoor spaces can provide information about settlement organization and social dynamics on a larger scale. In this paper, different contexts around ovens are presented and interpreted – from functional, economic, social, and symbolic perspective.

Central Heating Control Charts for the Economic Use of Energy in Residential Buildings

Methods and types (qualitative, quantitative or mixed) of control of central heating installations in residential buildings are presented. Measurements were made for a radiator in a central heating system that was powered by a heating node substation. The output temperature of the heat node supplying the residential building, in which the test stand was located, was compared with the measured supply and return temperature. Indoor room temperature, outdoor air temperature, inflow and outflow temperature on the vertical supplying the heater were also recorded and analysed. These data were compared with the control charts of the heat networks allowing for direct readings of the required feed water temperature for a given outdoor temperature according to the Heat Energy Enterprises data. The differences are accordingly presented. The actual measurements, read at the test stand located on the 2nd floor of the 4-storey building with input parameters of 90/70 °C during the entire month of December 2022, are recorded every 6 hours and are tabulated and displayed in comparison charts with the calculated parameters. Inflow and outflow temperatures values on the vertical supplying the heater and the values of outdoor temperature measured by a sensor were analysed. The temperatures supplied to the radiators in the apartments were also compared with the requirements of electronic heating cost allocators contained in the PN EN 834 standard. New design temperatures for the central heating installation were proposed due to the requirements of the electronic heating cost allocator.

The Effect of Heat Tracing Installation for Wax Prevention on Onshore Buried Swampy Pipelines

Transporting crude oil using pipelines is a widely adopted method globally. In one segment owned by PT. XYZ, especially in swampy areas, the fluid temperature tends to drop below the wax appearance temperature (WAT) during oil transportation. This is due to the relatively low temperature in swamp areas caused by heat loss to the environment. The solubility of paraffin in crude oil drastically decreases as fluid temperature drops, causing wax molecules to precipitate and deposit on the cold pipe walls. PT. XYZ employs chemical treatment by adding a pour point depressant (PPD) to lower the pour point temperature (PPT). However, PPD is effective only at certain temperatures, necessitating a study for alternative treatments. Another method involves installing heaters on the pipeline to reduce the viscosity of transported crude oil and enhance its flowability, either through direct heating or heat tracing using insulation with low thermal conductivity. Therefore, in PT. XYZ's case, an analysis is required to identify locations where fluid temperature decreases occur to ensure precise heater installation. Various software tools, including OLGA, have been developed to predict and describe wax deposition phenomena and temperature decreases along the pipeline. OLGA software can simulate locations of fluid temperature decreases in the pipeline, estimate heat loss along the pipeline, and simulate heat tracing technologies to prevent wax deposition. Simulation results indicate that wax deposition can be prevented by installing skin effect heat tracing with a heating power of 15 W/m and insulated with 2-inch aerogel, maintaining the oil temperature downstream at 157.34°F, well above the desired 115°F threshold.

Design and Experimental Tests of a Four-Way Valve with the Determination of Flow Characteristics for Building Central Heating Installations Using Solid Modeling

The article presents the design of a four-way valve, implemented in SolidWorks software (SOLIDWORKS® i 3DEXPERIENCE® Works Simulation) and used for central heating installations in buildings. The project was carried out in order to examine the innovative design of the medium mixing mechanism and to conduct strength and FMEA analysis. The innovative solutions proposed by the authors in this work will allow valves of this type to meet stringent environmental standards. These standards are currently being introduced for this type of structural element of machine parts as part of the energy transformation of buildings. Potential failures occurring in individual elements of the four-way valve were also tested using Failure mode and effects analysis. In addition, strength tests were performed in SolidWorks software using static analysis, and optimization tests were performed on the refrigerant in terms of its impact on the environment. The characteristics of the tested materials in the valve design show that the best materials are brass and stainless steel. Brass has a Poisson’s ratio of 0.33, a tensile strength of 478.4 MPa and a yield strength of 239.7 MPa. In turn, stainless steel is characterized by the following parameters: Poisson’s ratio of 0.27, tensile strength of 685 MPa and yield strength of 292 MPa. The designed valve reduces energy consumption by 30% through a properly designed medium flow with the appropriate selection of materials. Moreover, the design reduces the thickness of the contaminant layer by 0.17 mm, with a capacity factor of −2.50% and an evaporator Δp of 3.10% (53 kPa). The performed research provides knowledge on the subject selection of appropriate material, a description of the potential failures of the structural elements of the designed four-way valve and methods of counteracting these failures. The article presents the optimization role of the tested component in the context of sustainable development.

Selection of Renewable Energy Sources for Modular and Mobile “Green Classroom” Facilities

This article aims to demonstrate the technical capabilities and effectiveness of an energy production and management system for school facilities using a modular solution. The system is assumed to generate electricity from renewable sources, such as wind or sun. The potential of renewable energy sources in Cracow, Poland, was assessed, with a focus on solar energy (photovoltaic panels, PV). Taking into account the installation of heating and other equipment, an analysis of the facility’s electricity demand was carried out. The study recommended the use of a heat pump system to heat and cool the facility. Renewable energy sources will meet 81% of the facility’s projected annual demand, according to the study. An analysis of the energy consumption and production profiles shows that almost 69% of the energy produced by the PV panels is consumed on site. Of the remaining energy, 31% is fed back into the grid and sold to the grid operator or used by other facilities within the shared settlement. The overall balance results in a small electricity deficit that must be covered by the grid. If suitable sites are available, the facilities under study could consider installing a wind turbine as a potential supplement to the energy deficit.

A Review of Possibilities and Challenges of Pit Thermal Energy Storages in Swedish District Heating Networks

The use of pit thermal energy storages (PTES) enables higher solar fraction in district heating networks by counteracting the mismatch between heat demand and production in solar district heating (SDH) installations. Capital costs linked to land areas with site-specific geological conditions are the deciding factors for PTES constructions. This study investigates non-technical and technical factors for the implementation of PTES in Swedish district heating networks. Having several SDH and PTES installations in operation the country of Denmark is used as a reference. This study, based on literature review, discusses the drivers and challenges for the use of PTES in district heating networks.

Energy vulnerability of detached home owners in Finland: An explorative study

Vulnerability to energy poverty occurs when a household has difficulties to meet adequate energy service levels. Recent energy crises manifested the consequences of energy vulnerability also in the Nordic countries. This study brings evidence on energy poverty in Finland, using a large household energy survey dataset (N = 4,295). The ten-per-cent limit threshold is used to measure objective energy vulnerability and the subjective measure is based on the regularity of households’ self-assessed psychological burden regarding their energy expenditures. In our dataset, 18 % of households in detached and semi-detached houses were objectively energy poor and 27 % felt a regular energy-cost burden. Heating type, building age, education level and gender were significant determinants. Ownership of a ground-source heat pump and usage of solid wood reduces winter energy poverty in Finland. Women, particularly in older age groups were significantly more vulnerable than men. For some groups, objective and subjective measurement produced distinctively different results. Households using oil heating in a hybrid heating arrangement were more vulnerable in the objective measurement but they did not feel a similar subjective energy cost burden. Families with children felt subjectively more burdened by their energy expenses than other groups, but they were not more energy-poor along the objective measurement. This is one of the first energy vulnerability studies based on large amount of citizen survey data in Finland and we recommend that further research focuses particularly on how different social groups can access and use different heating installations as this is a key determinant of energy vulnerability in countries with substantial domestic heating energy needs.

Applied Mathematics in the Numerical Modelling of the Electromagnetic Field in Reference to Drying Dielectrics in the RF Field

The processing of dielectric materials in the radio frequency field continues to be a concern in engineering. This procedure involves a rigorous analysis of the electromagnetic field based on specific numerical methods. This paper presents an original method for analysing the process of drying wooden boards in a radio frequency (RF) installation. The electromagnetic field and thermal field are calculated using the finite element method (FEM). The load capacity of the installation is also calculated, since the material being heated in the radio frequency heating installations is placed in a capacitor-type applicator. A specific method is created in order to solve the problem related to mass, a quantity which tends to change during the drying of the dielectric. In addition, special consideration is given to issues regarding the coupling of the electromagnetic field and the thermal field, along with aspects pertaining to mass. These are implemented numerically using a program written in the Fortran language, which takes the distribution of finite elements from the Flux2D program, the dielectric thermal module, intended only for the study of RF heating. The results obtained after running the program are satisfactory and they represent a support for future studies, especially if the movement of the dielectric is taken into account.

Simulation of a Solar Domestic Water Heating System with Different Collector Efficiences and Different Volumen Storage Tanks.

This paper shows the modeling and dynamic simulation, of a domestic solar water heating installation. The results of simulations performed on an annual basis for a solar system, operated in Santander (Spain), which provides hot water for a family (four persons) are presented. The installation consists in a solar flat collector, a water storage tank, a source of auxiliary energy, and a device for blending water. The mathematical model is used to evaluate the annual variation of the solar fraction respect to the volume of the storage tank, demand hot water temperature required, difference of this temperature and preset storage tank water temperature, and consumption profile of the domestic hot water demand. The results for a number of designs with different storage tank volumes, show that the systems with greater volume yield higher solar fraction values. However, when a larger storage tank volume is used, the solar fraction is less sensitive to a variation of these operation parameters. The results of this simulation may be used to design a solar collector system.

Assessment of Solar Heater Installations in Urban and Rural Settings

Assessment of Solar Heater Installations in Urban and Rural Settings

ОБОСНОВАНИЕ ЭНЕРГОСБЕРЕГАЮЩЕЙ ФУНКЦИОНАЛЬНОЙ СХЕМЫ АККУМУЛЯЦИОННОЙ УСТАНОВКИ ДЛЯ НАГРЕВА ВОДЫ НА ФЕРМАХ КРС

Analysis of electric energy consumption on cattle farms has shown that hot water supply is one of the energy-intensive technological processes on such farms. In order to save energy resources when heating water, a functional scheme of an accumulator installation has been developed that allows heating water for watering cows and providing technological needs. The standard water temperature for drinking is 12-15 degrees Celsius, for technological needs - 55-65 degrees Celsius. (Research purpose) The research purpose is substantiating and developing a functional scheme of an energy-saving installation for heating water using solar radiation for technological needs and thermal energy of ventilation air removed from the premises for watering cows on cattle farms. (Materials and methods) Applied patent search on the websites of Rospatent and Yandex.Patents. The analysis of analytical calculation dependencies was performed to determine the main technical characteristics of water heating installations for animal watering and technological purposes. (Results and discussion) A functional scheme of the hot water supply installation was proposed, including a water heater for technological needs using solar radiation energy and a water heater for animal watering using a thermoelectric heat pump and the heat of the ventilation air removed from the farm premises. (Conclusions) Developed a functional scheme of an accumulative water heating unit for watering cows and technological needs on cattle farms. It has been shown that the proposed scheme allows using the heat of the air removed from the premises and the renewable heat of solar radiation as alternative sources to traditional methods of heating water. The possibility of using low-potential thermal energy of the removed ventilation air for hot water supply of the animal watering system using a thermoelectric heat pump and heat pipes, as well as a solar collector for heating water for the technological needs of the farm, was investigated.

МОДЕЛЮВАННЯ ЕЛЕКТРОТЕПЛОВИХ ПРОЦЕСІВ В УСТАНОВЦІ ІНДУКЦІЙНОЇ ТЕРМООБРОБКИ АЛЮМІНІЄВИХ ЗЛИВКІВ І ВИЗНАЧЕННЯ ШЛЯХІВ ПІДВИЩЕННЯ ЇЇ ЕФЕКТИВНОСТІ ПРИ ПРЕСУВАННІ КАТАНКИ ДЛЯ СИЛОВИХ КАБЕЛІВ

A computer mathematical model is presented for the study of electrothermal processes in the installation of induction heat treatment of cylindrical aluminum ingots during pressing of wire rod for the manufacture of aluminum wire for power cables. The model makes it possible to determine energetically and technologically appropriate electromagnetic and thermal modes of induction heat treatment of ingots at a given voltage on the inductor. The results of the study of a typical installation for heating aluminum blanks for the purpose of their subsequent gradient pressing using a single-phase single-layer cylindrical inductor made of a rectangular copper tube are presented. Temperature distributions along the length of the aluminum blanks, as well as in the cross-sections of the billets at the output of the inductor, were obtained. A slight difference in the calculated electromagnetic and thermal parameters from the similar parameters of the operating installation confirmed the adequacy of the developed model. Ways to increase the efficiency of the induction heating installation by optimizing the profile of the inductor turns are considered. The influence of the thickness of the wall of the copper tube of the inductor close to the workpiece on the efficiency of the installation was determined and it was shown that its optimal thickness is at the level of the depth of penetration of the electromagnetic field into the metal. The possibility of using a three-phase power supply of the inductor was also investigated and it was shown that in this case it is most appropriate to use a phase angle shift between voltages of 60 el. degree. References 10, tables 2, figures 7.

Параметрическая идентификация и оптимальное управление процессом индукционного нагрева

In the paper the experimental induction heating installation for through heating of steel cylindrical workpieces is considered. It is well known that the use of an industrial heating system presupposes incomplete information about its main characteristics due to the complex nature of changes in some parameters both from the ambient temperature and from the temperature of the heated part. These parameters primarily include the coefficients of convective and emissive heat transfer from the surface of the workpiece. At the first step, it is necessary to obtain the values of unknown parameters, which also include the voltage of the power source, and then solve the optimal control problem. The problem of identifying these parameters is solved using the alternance method of parametric optimization of systems with distributed parameters, using experimental data from thermocouples. The obtained values of unknown parameters are then used in a numerical finite-element FLUX model of the considered process. Based on the developed model, the problem of time-optimal control with an additional phase restriction on the maximum temperature is formulated. This problem is solved using the alternance method. The solution of the problem made it possible to obtain a emperature field with a maximum deviation of 32 °C from the required temperature T* = 1 200 °C. This value is less than 3% of the desired temperature value and fully meets the technological requirements for induction through heating processes prior subsequent plastic deformation. The maximum temperature in this case does not exceed the maximum permissible value of 1 300 °C during the entire heating process.

Analyzing the incidence of silicosis across various industries in Taiwan: a study of occupational disease surveillance by linking national-based workers’ and medicoadministrative databases

ObjectivesThis study aimed to establish an occupational disease surveillance system by identifying high-risk industries for silicosis in Taiwan using a national database linkage approach. MethodsThe study was based on a comprehensive analysis of benefit claims from the National Labor Insurance Research Database and medical records from the National Health Insurance Research Database between 2004 and 2020, providing coverage for more than 88.5% of the workforce and 99.9% of citizens. Silicosis was defined as having received compensation for labor insurance benefits or having received a diagnosis of silicosis (International Classification of Diseases, 10th Revision: J62 or International Classification of Diseases, Ninth Revision: 502). The study used the International Standard Industrial Classification of All Economic Activities for industry-specific classification. Cox proportional hazard models were used to compare the silicosis incidence and risk among each industry and identify high-risk industries for silicosis. ResultsThis study analyzed 1466 cases of silicosis between 2004 and 2020 and found that 28 industries had incidence rates of over 40 cases per 100,000 workers, indicating more than double the risk of developing silicosis. Of these industries, 14 were considered high risk (relative risk of over four times). Among these, this study identified industries rarely mentioned in the past, such as wholesale of brick, sand, cement, and products, artistic creation, landscape construction, and materials recovery. Stratification by years of work experience reveals those industries such as quarrying of stone, sand, clay, and other mining, construction of buildings, landscape construction, site preparation, foundation and structure construction, building completion and finishing, manufacture of ships, boats, and floating structures, and plumbing, heat, and air conditioning installation display higher hazard ratios for individuals with <10 years of work experience. ConclusionsThe current surveillance system has identified certain industries that are at a higher risk of developing silicosis, which could be used for future occupational epidemiological surveys and targeted preventive measures in these sectors.

A comprehensive framework for eco-environmental impact evaluation of wastewater treatment plants: Integrating carbon footprint, energy footprint, toxicity, and economic assessments

The need for clear and straightforward guidelines for carbon footprint (CFP) and energy footprint (EFP) evaluations is critical due to the non-transparent and misleading results that have been reported. This study aims to address this gap by integrating CFP, EFP, toxicity, and economic assessments to evaluate the eco-environmental impacts of wastewater treatment plants (WWTPs). The results indicate that the total CFP was below 0.6 kg CO2/kg COD removed, which is attributed to CO2 offset and biogas recovery. However, site-specific EFP varied considerably from 482.7 to 2294 kgCO2/kWh due to design differences of WWTPs and their aeration and mixing energy demand (46.96–66.1%). The use of crude oil and natural gas for electricity generation significantly increased EFP, CFP, and carcinogenic human toxicity. In contrast, a combined heat and power (CHP) installation enabled energy recovery ranging from 12.09% to 65.65%. Construction costs dominated the highest share of total costs (85.43%), with indirect construction costs (42.9%) and operation labor costs (61.4%) being the primary elements in the total net costs. It is worth noting that site-specific CO2 emission factors were used in the calculations to decrease model uncertainty. However, to improve modeling reliability, we recommend modifying the regional CO2 emission factor and focusing on emerging technologies to recover energy and biogas.