Conventional Heating Systems Research Articles

A Review of the Building Heating System Integrated with the Heat Pipe

The heat pipe (HP) is widely applied in the thermal management field at present. In order to make use of the low-grade and renewable energies to maintain building thermal comfort in the heating season, more and more studies with respect to improving the thermal performance of the building heating system integrated with the HP (BHSIHP), such as the floor heating system integrated with the HP (FHSIHP), the thermal storage wall heating system integrated with the HP (TSWIHP), conventional wall integrated with the HP (WIHP) and radiator heating system integrated with the HP (RHSIHP), are conducted. This paper aims to summarize different types of HPs applied in the building heating system and offers an overview of the thermal performance improvement for the BHSIHP. The thermal response, thermal conductivity, thermal resistance, heat capacity, heat transfer coefficient, temperature distribution, thermal storage and heat release capacity are always selected to investigate characteristics of the BHSIHP. Results show that the thermal performance of the FHSIHP, the TSWIHP, the WIHP and the RHSIHP is more outstanding than that of the conventional heating system. The thermal performance of the BHSIHP is affected by heat source temperature, installation tilt angle, working fluid, and filling ratio of the HP. The heat source temperature, which positively affects the performance of the BHSIHP, is crucial for the selection of the working fluid and filling ratio. However, the performance of the BHSIHP is increased first and then decreased with the increase of the installation tilt angle. The optimal filling ratio of the working fluid has been proven not to be a fixed value.

Loudness and preference judgments for noises of a heat pump

An increasing number of heat pumps have recently been installed to replace conventional heating systems to provide more environmentally friendly and energy-efficient indoor heating. Most commonly, air-to-water heat pumps are chosen. However, the sounds of their fan and compressor can lead to noise complaints and can reach the limit of noise emission regulations. To achieve a more pleasant environment, research is conducted to reduce the perceived noise of heat pumps. As part of an interdisciplinary research project, this study aims to investigate the annoyance ratings of a heat pump and characterize them in terms of equivalent loudness and preference penalties. The study uses a two-alternative forced-choice (2AFC) method with a 1-up-1-down rule to measure the point of subjective equality for six stimuli representing different operation states of the investigated device. This experiment aims to identify differences between loudness and preference, and combined with an evaluation of psychoacoustic parameters, its results are used to improve the acoustics of heat pumps and the overall user experience.

The Effects of Different Cooking Systems on Changes in the Bioactive Compounds, Polyphenol Profiles, Biogenic Elements, and Protein Contents of Cauliflower Florets

In the current study, we examined the effects of boiling cauliflower in a pressure cooker, conventional boiling, conventional heating, and microwave heating on the chemical components, total phenol, flavonoids, antioxidant capacity (DPPH test), phenolic compounds, and mineral contents of cauliflower florets to reveal the differences between these cooking methods. Cauliflower is generally consumed either boiled or cooked in dry heat. In this study, different boiling and dry heat cooking methods were tried to reveal the changes in phytochemical composition and protein and mineral contents of cauliflower florets. Depending on the cooking methods of the cauliflower florets, the total phenolic and flavonoid contents of the cauliflower florets were determined to be between 273.72 (conventional heating) and 731.01 mg GAE/100 g (microwave heating) and 142.02 (conventional heating) and 797.10 mg/100 g (conventional boiling), respectively. The antioxidant capacity results of cauliflowers were found to be between 8.30 (conventional heating) and 33.69 mmol/kg (fresh). Statistically significant differences were detected in the moisture, total phenol, total flavonoid, and antioxidant activity values of cauliflower depending on the cooking techniques applied (p < 0.05). The gallic acid and 3,4-dihydroxybenzoic acid values of fresh and cooked cauliflowers were identified to be between 10.93 (microwave heating) and 194.79 mg/100 g (boiling in pressure cooker) and 17.58 (conventional heating) and 145.80 mg/100 g (boiling in pressure cooker), respectively. In general, the lowest amounts of phenolic compounds were defined in cauliflower samples boiled with a conventional heating system, followed by cauliflower samples cooked with the microwave heating method. Considering the component amounts as a result of cooking, the highest phenolic component amounts were specified in the cauliflower sample cooked by boiling in a pressure cooker. The protein quantities of fresh and cooked cauliflowers were determined to be between 16.11 (fresh) and 19.79% (microwave heating). The K and S contents of fresh cauliflowers and cauliflowers cooked with different blanching methods were specified to be between 19,647.62 (conventional boiling) and 35,130.01 mg/kg (conventional heating) and 3196.54 (boiling in pressure cooker) and 5105.65 mg/kg (microwave heating), respectively. The K, Mg, S, Fe, Cu, Mn, and Zn results of cauliflowers cooked in an oven and microwave were higher than those cooked using the control and boiling methods.

A cold start strategy in fuel cell vehicles to provide instant hot air for stacks and passengers by vortex tubes

Green vehicles, particularly Fuel Cell Vehicles (FCVs), offer a promising solution to environmental challenges. One of the major obstacles for FCVs is starting the Polymer Electrolyte Membrane (PEM) fuel cell stacks in subfreezing temperatures, where the water produced by chemical reactions can freeze and hinder the cold-start process. Preheating the inlet air to the stack up to 80 °C is an effective approach to overcome this issue. However, conventional heating systems, such as electric heaters, are unable to heat the air quickly enough. This paper introduces a novel heating method to enhance the cold-start capability of FCVs. The proposed solution involves integrating vortex tubes, which are simple and cost-effective, with the vehicle’s existing compressor. This system not only preheats the inlet air to the stacks but also provides warm air for the passengers simultaneously. By developing a 3D-CFD model of the vortex tube, the results demonstrate that the system can preheat the inlet air to the stacks from −30 °C to 80 °C and the air entering the passenger compartment from −30 °C to nearly 37 °C in just about 5 s. In comparison, conventional heating systems require over 600 s (10 min) to achieve the same temperature rise.

Energy and environmental impacts of air-to-air heat pumps in a mid-latitude city

Heat pumps (HPs) have emerged as a key technology for reducing energy use and greenhouse gas emissions. This study evaluates the potential switch to air-to-air HPs (AAHPs) in Toulouse, France, where conventional space heating is split between electric and gas sources. In this context, we find that AAHPs reduce heating energy consumption by 57% to 76%, with electric heating energy consumption decreasing by 6% to 47%, resulting in virtually no local heating-related CO2 emissions. We observe a slight reduction in near-surface air temperature of up to 0.5 °C during cold spells, attributable to a reduction in sensible heat flux, which is unlikely to compromise AAHPs operational efficiency. While Toulouse’s heating energy mix facilitates large energy savings, electric energy consumption may increase in cities where gas or other fossil fuel sources prevail. Furthermore, as AAHPs efficiency varies with internal and external conditions, their impact on the electrical grid is more complex than conventional heating systems. The results underscore the importance of matching heating system transitions with sustainable electricity generation to maximize environmental benefits. The study highlights the intricate balance between technological advancements in heating and their broader environmental and policy implications, offering key insights for urban energy policy and sustainability efforts.

Análise técnico-econômica da implantação de um sistema de aquecimento solar para suprir a demanda de água quente dos vestiários de um abatedouro de aves

The use of electricity to heat bath water is still quite common in Brazil, especially in the South and Southeast regions. This practice represents about 24% of the total energy consumption in the residential sector. Additionally, its usage is concentrated between 6 and 9 PM, leading to serious issues in energy generation and distribution during this interval. Given the importance of rationalizing the electricity consumption, the aim of this paper was to conduct a technical-economic analysis for the implementation of a hybrid solar heating system to supply the demand for hot water in the bathrooms of a poultry slaughterhouse located in the Western region of Paraná. For this, different scenarios of usage were developed, where the type of solar collector and the auxiliary power source were varied and a comparison between the alternatives and the conventional water heating systems was made. A calculation routine based on the F-Chart method was used to size the alternative systems. The Net Present Value (NPV), the Internal Rate of Return (IRR) and the discounted Payback were used as decision-making criteria. All configurations sized in this study were proved to be viable. However, the most interesting one, from a technical-economic point of view, was the combination of the flat-plate solar collectors and the electric auxiliary power source. The comparison of this scenario with the conventional source showed an NPV of R$ 92,916.84, an IRR of 59.9%, and a payback period of 1 year and 11 months.

An off-grid solar district energy system with borehole thermal energy storage: Life cycle assessment in a subarctic region

Nunavik, a remote subarctic region covering the northern third of Quebec, Canada, relies heavily on diesel to meet residential heating demand. Solar district heating (SDH) with borehole thermal energy storage (BTES) has been developed there as one of the most promising solutions that can break the dependence on fossil fuels and develop renewable energy resources locally. Developing an SDH-BTES in Nunavik is not only a technical and economic consideration, but also an environmental deliberation. Therefore, in this study, a cradle-to-grave life cycle assessment (LCA) of both SDH-BTES and conventional systems are performed for this area. The SDH-BTES system is defined as a heating system for a community comprising 1500 m2 gross solar area and 150 borehole heat exchangers with a depth of 30 m which is modeled to analyze its environmental performance. The results are presented comparatively with the conventional heating system consisting of local household diesel furnaces. Fifteen various impact categories are introduced for the comparison and contribution of main components (solar subsystem, auxiliary subsystem, transportation, and disposal) are analyzed individually. The present analyses show that SDH-BTES performs better than local diesel furnaces regarding human health, climate change, and resources. However, ecosystem quality impact of SDH-BTES system is slightly higher than the conventional domestic diesel furnaces due to the large land occupation of underground thermal heat storage and drilling process. The SDH-BTES system can improve environmental impact by 21 % compared to the conventional system and reduces CO2 emission by 22.4 %.

Case study: reducing heating energy consumption in a high tunnel greenhouse with renewable energy and microclimate control by bench-top root-zone heating, bench covers, and under-bench insulation

Appalachian State University's Nexus project designed an efficient greenhouse heating system that integrated renewable energy and root zone heating technology to reduce the greenhouse heating energy burden on local farmers and installed it at local cooperative farms. This study analyzed 5 years of data from 2018 to 2022 to investigate the energy savings and microclimate control effectiveness of the Nexus heating system installed at Springhouse Farm in North Carolina, USA. By varying bench cover materials, bottom insulation, and the number of loops of root zone tubing, the different soil temperatures required for plant types and growth stages were achieved with a single temperature controller. A root zone heating fluid of 32.2 ℃ satisfactorily maintained the germination soil between 20 and 25 ℃ in March 2019 with an average outside temperature of 4.8 ℃ and an average low temperature of − 0.4 ℃. Growing soil maintained an average temperature of 15 ℃ with bottom insulation and an average of 11–12 ℃ without bottom insulation. Compared to the conventional heating system (a forced-air propane unit heater alone), weather-adjusted propane consumption (propane usage divided by heating degree days) was reduced by 65% with the Nexus system alone and 45% with the Nexus system and unit heater together. It shows that the Nexus system has significantly reduced greenhouse heating energy consumption and maintained productive conditions. The renewable energy fraction ranged only 9–13% of the total thermal energy used due to the high inlet temperature entering the solar thermal collector. This can be improved by separating the heat storage and backup heat source.

The impact of conventional cigarettes, e-cigarettes, and tobacco heating systems on the oral mucosa

Relevance. Over the past few years, the popularity of nicotine-containing substances and tobacco heating systems has continued to grow, while the demand for conventional tobacco leaf cigarettes has been falling. Electronic cigarettes consist of a heating system and a liquid with various flavorings. During the operation of the heating stick, the liquid is converted into an aerosol, which the user needs to inhale. First of all, the hot steam comes into contact with the oral cavity. The aerosol components settle on the oral mucosa, the approximal surfaces of the teeth, penetrating the body with a saliva current, expose the oral cavity to prolonged exposure, causing various changes in the oral cavity and causing discomfort to the smoker. This problem is urgent and based on the above, it is necessary to study all possible effects of cigarettes and electronic nicotine delivery systems on the human body.Purpose. To assess the impact of nicotine-containing products and smokeless tobacco on the oral mucosa.Materials and methods. A cohort of 98 patients, aged 20 to 60, was recruited for the study. Participants were divided into four groups: Group 1 consisted of conventional cigarette smokers; Group 2, users of vapes; Group 3, users of IQOS; and Group 4 included patients who used all three device types interchangeably.Results. The investigation identified a direct correlation between the participant's age, the device used, and their level of oral hygiene. The poorest oral hygiene was seen in Group 4, where individuals used a combination of conventional cigarettes, vapes, and IQOS. Although a majority acknowledged the harmful effects of tobacco products, only 33 participants were aware of the negative impacts associated with vapes and IQOS.Conclusion. The lack of regulation and awareness of the health risks associated with IQOS and vaping pose substantial challenges for healthcare, indicating a need for more research into these issues.

Analysis of the Wider Potential for Heat Pump and Geothermal Energy Integration in Traditional Systems and Grids


 
 
 The current energy security crisis is primarily a heating crisis. Space and water heating accounts for almost one-third of the EU’s final energy consumption, and unfortunately, around 62% of this demand is still met by fossil fuels. In this context, heat pumps, geothermal energy, and other renewable energy sources emerge as crucial technologies offering effective solutions to enhance energy efficiency and decrease dependence on fossil fuels as well as to achieve the EU energy and climate goals.
 This article focuses on the analysis of the potential and opportunities of using heat pumps and geothermal energy in conventional heating systems and district heating networks. This topic requires an in-depth analysis of the current state, challenges, benefits, and prospects of these technologies in the EU market. By examining the possibilities for wider adoption and discussing the associated factors, the article aims to provide valuable insights into and recommendations for the advancement of heat pumps and geothermal energy in the EU, along with the presentation of some case studies in this field.
 
 

Technical, Environmental, and Economic Analysis Comparing Low-Carbon Industrial Process Heat Options in U.S. Poly(vinyl chloride) and Ethylene Manufacturing Facilities.

Electrification and clean hydrogen are promising low-carbon options for decarbonizing industrial process heat, which is an essential target for reducing sector-wide emissions. However, industrial processes with heat demand vary significantly across industries in terms of temperature requirements, capacities, and equipment, making it challenging to determine applications for low-carbon technologies that are technically and economically feasible. In this analysis, we develop a framework for evaluating life cycle emissions, water use, and cost impacts of electric and clean hydrogen process heat technologies and apply it in several case studies for plastics and petrochemical manufacturing industries in the United States. Our results show that industrial heat pumps could reduce emissions by 12-17% in a typical poly(vinyl chloride) (PVC) facility in certain locations currently, compared to conventional natural gas combustion, and that other electric technologies in PVC and ethylene production could reduce emissions by nearly 90% with a sufficiently decarbonized electric grid. Life cycle water use increases significantly in all low-carbon technology cases. The levelized cost of heat of viable low-carbon technologies ranges from 15 to 100% higher than conventional heating systems, primarily due to energy costs. We discuss results in the context of relevant policies that could be useful to manufacturing facilities and policymakers for aiding the transition to low-carbon process heat technologies.

Factors influencing precise control of room temperature for floor heating systems in severely cold regions of China

Precise control of room temperature for floor heating systems is a key step toward intelligent heating, which is of great significance in achieving thermal comfort and energy savings. Generally, the room temperature is controlled by thermostats that are placed on a wall, far away from the occupied zone. This may cause large temperature control deviation and cannot satisfy thermal comfort of the occupants. Based on the theory of the building thermal design, this study investigated the factors influencing the heating room temperature and temperature control deviation by combining a field experiment with a numerical simulation, providing a thermostat installation location strategy. The results show that air infiltration and solar radiation are the two main factors affecting the indoor temperature field. For conventional heating systems widely used in severely cold regions of China, it is not recommended to install thermostats near the occupants, but rather on the walls. The installation location should comprehensively consider room size, air infiltration, and solar radiation. To avoid the influence of outdoor factors and internal heat sources, 1.5 m can be used as the optimal installation height. These findings provide reference for the precise control of room temperature for floor heating systems.

On the Possibility of Using CHP From a 1.4MW Direct Fuel Cell at Kettering University Engineering Building – A Demonstration Study

The concept of using a distributed power generation and a combined heat and power principle – CHP in public buildings, commercial facilities is widely gaining public acceptance as a result of reduced energy cost, reliable power supply and environmental and health issues. By using the exhaust heat from a high temperature fuel cell at 400 oC for cogeneration, space heating, to provide warm water for facility use - (swimming pool and sporting locker room) and cooling in chillers at no additional cost, we reduce energy cost and preserve the environment. By bottoming cycle, the efficiency of the entire system is increased. A study is conducted to compare the economic impact of using the CHP system against the conventional heating system using furnaces.

In Situ Performance Analysis of Hybrid Fuel Heating System in a Net-Zero Ready House

The global population’s growth and increased energy consumption have driven greenhouse gas (GHG) emissions. In Canada, the residential sector accounts for 17% of secondary energy use and 13% of GHG emissions. To mitigate GHG emissions, promoting renewable energy and efficient heating systems is crucial, especially in cold climates like Canada, where there is a heavy dependency on fossil fuels for space heating applications. A viable solution is hybrid fuel heating systems that combine electric-driven air-source heat pumps (ASHPs) with natural gas tankless water heaters (TWHs). This system can alternate its operation between the ASHP and TWH based on efficiency and real-time energy costs, reducing grid peak demand and enhancing resilience during power outages. Although lab experiments have shown its benefits, in situ performance lacks evaluation. This study analyzes the in situ energy performance of a net-zero ready house and its hybrid fuel heating system, assessing energy consumption, hourly space heating output, and system heating performance. HOT2000 is a robust simulation software designed for assessing energy consumption, space heating, cooling, and domestic hot water systems in residential buildings. An artificial neural network model was developed to predict the energy performance of the hybrid fuel system, which was used as a substitute for monitored data for evaluating the HOT2000’s simulation results under the same weather conditions. Therefore, this study proposes a comprehensive framework for the in situ performance analysis of hybrid fuel heating systems. This study then, using HOT2000 energy consumption results, evaluates the life cycle costs of the hybrid fuel system against conventional heating systems. Furthermore, this study proposes an economical control strategy using in situ data or manufacturer specifications.

Economic viability of under floor heating system: a case study in Beirut climate

This paper explores the economic feasibility of the underfloor heating system for the climatic conditions of Beirut. A case study of a typical residential room (150 m2 ) is selected to compare its heating energy requirement when using either the conventional convective heating system or the underfloor heating system at similar comfort and indoor air quality conditions. Two mathematical models are developed, a steady space thermal model to establish the energy consumption at the peak load and a transient simulation model to find the energy consumption during the winter heating season. In addition, the economic feasibility of the underfloor heating system is assesd when integrated with solar energy. Based on the steady space model, the calculated peak heating load is reduced by 20% when the test space is heated by the underfloor heating system and a thermal comfort level of PPD 18.3% is achieved for a floor temperature of 27.4 ºC. The simulation results of the transient space model indicates that the seasonal heating energy consumption is reduced by 18% and that the yearly energy savings is $104 for an on-off control strategy that maintains a PMV comfort level greater than -0.5. The pay back period of the underfloor heating system is 10 years for an initial incremental cost of $850. When integrated with 10 solar collector units, the yearly energy savings of the integrated system is increased to $350 and the pay back period is 14 years.

Real-time outdoor experiment and performance analysis of dual-coil heat exchanger integrated thermal energy storage

Integrating a thermal energy storage system into a solar water heater enables a continuous heat supply to ensure hot water is available for household uses throughout the day. This research emphasizes integrating TES units into solar water heating systems. The overall performance of flat plate solar water heaters for a regular (conventional) solar water heating system and a solar water heating system integrated with TES using phase change material (PCM) are analyzed. This innovative design ensures efficient heat capture from the sun, storing it in the phase change material for later use, guaranteeing a sustainable and cost-effective solution for hot water needs. A split PCM tank is integrated within the solar water heating network for the second scenario and is made of a 25 L filled with a phase change material that acts as the thermal storage medium. The PCM tank has a dual-coiled heat exchanger to aid the heat transfer process with paraffin wax as the phase change material. The parameters that are looked into from the conventional and TES-integrated solar water heating systems include the water temperature profiles throughout the entire solar water heating networks and the PCM's temperature distribution throughout the day. A customized water draw schedule is adapted to represent the average hot water usage of a typical household in Kuala Lumpur. Findings reveal that the TES-integrated solar water heating system can be 21 % more efficient than the conventional system due to the lesser heat losses and prolonged hot water supply. The maximum efficiency obtained is about 82 %, and energy can be saved about 50 % from the electric heater. The maximum energy storage is at the 50 °C temperature controller's setting and is feasible for the existing conventional solar water heaters.

HYDROFORMYLATION OF METHYL ACRYLATE USING A PALLADIUM SCHIFF BASE CATALYST UNDER SYNGAS SOURCE

Hydroformylation of methyl acrylate can be carried out in a short time and without the use of syngas under microwave dielectric heating. We show that a Palladium Schiff base catalyst can control regioselectivity in heterogenous hydroformylation. Microwave irradiation, which produces greater yields in less reaction time and uses less energy than conventional heating systems, may carry out the hydroformylation reactions of the Methyl acrylate with greater efficiency and sustainability without using the CO and H2 cylinder. This method offers a hopeful prospect for a more sustainable future in chemical synthesis. Hydroformylation of Methyl acrylate using (PdL2)Cl2) (where L= N- (diphynylmethylide) Aniline (LA) and (E)-1-(2-methoxyphenyl)-N-phenylmethanimine (LB), as a catalyst at 120 oC for 20 minutes in the microwave and at 200 oC, 5 h in the conventional heating. This work demonstrates that methyl acrylates can be hydroformed in glyoxylic acid using a palladium catalyst system, producing the intended products, aldehydes, in outstanding yields and selectivities. Moreover, solventless synthesis using specific catalyst systems has improved catalytic performance compared to solvent-based reactions, attributed to higher reactant concentrations. Palladium complexes PdLA and PdLB gave excellent aldehyde yields in the microwave, 89 % (l/b ratio 96:4) and 86 % (95:5), respectively, over the conventional heating, which were analyzed by 1HNMR and GCMS spectroscopic techniques.

Analysis and simulation of ecological environment response of ground source heat pump system under thermal equilibrium

This work is designed to study the thermodynamic equations of groundwater source heat pump in hot summer and cold winter, and to determine the optimal operating conditions of groundwater source heat pump by means of the thermodynamic analysis of source heat pump, flow, unit, pump power, evaporation side and condensation side. Practice has proved that the equipment runs stably and with high efficiency. By comparison, the ground source heat exchangers were compared with conventional chillers and boiler. The results showed that the underground heat pump had higher energy consumption, lower primary energy consumption, reduced CO2 emissions, and reduced environmental pollution during operation, proving that the underground heat pump had obvious advantages over the conventional cooling and heating system. Meanwhile, this also shows that the long-term operation of ground heating system has caused the instability of ground heating system, the accumulation of cold and heat in ground-water, and the variation of ground temperature, which not only reduces the system efficiency, but it also affects the physical properties of soil itself and the soil heat flow, and will also cause changes in soil microbial environment and vegetation ecological environment, thus affecting the whole ecological environment.

Improvement of the heating load calculation through analysis of the heating capacities using thermal simulation

The present study addresses the growing significance of renewable energies as a replacement for conventional gas and oil heating systems. Given the dynamic nature of these renewable energies, the integration of thermal simulations into building planning is becoming increasingly important. However, a significant portion of German standards remains static, especially the heating load calculation according to DIN EN 12831-1:2017-09. As the norm calculates the heating performance based on the day with the lowest temperatures, there is a risk that, among other things, the supply temperature will be incorrectly designed on milder days. The heating curve plays a crucial role, but it is usually adjusted only after the building's heating system is installed.

Solar-Air Source Heat Pump Water Heater for Scorching Climatic Condition: Energy, Exergy, Economic and Enviroeconomic (4E) Exploration for Sustainable Future

As solar-powered air source heat pump is an emerging water heating technique in scorching climatic conditions, it is necessary to explore their performance in terms of energy, exergy, economic, and environeconomic (4E) perspective. Henceforth, current research experimentally investigates and reports on 4E of Direct Expansion Solar-Air Source Heat Pump water heater for hot regions. A heat pump with a dual source evaporator is proposed in two working modes: solar air source mode and air source mode. The impact of ambient conditions on the thermal performance, such as power consumption, evaporator and condenser capacity, heating time, coefficient of performance, and exergy efficiency of the heat pump water heating system in both the working modes, was experimentally investigated. Results depict the coefficient of performance of the proposed heat pump system in solar air source mode and air source mode in the range of 2.37-5.05 and 2.26-4.21, respectively. On average, the system heating time in solar air source mode is 16.5% shorter than in air source mode. Based on the simulation results, compared to a conventional standard electric heating system, the payback period and lifetime carbon-dioxide mitigation savings cost of the proposed dual-source heat pump system are about 616 days and $179866, respectively.