Air Heating System Research Articles

Impact of concrete durability improvement on building life cycle carbon emissions: a case study of residential buildings in Northwest China.

Building carbon emissions (CE) have become the focus of the current topic, but there is still no mature typical building life cycle theory method from the perspective of building materials, and the research on the relationship between building durability and building life cycle is still insufficient. To this end, this study established a detailed calculation method for building carbon emissions (CE) and divided the building life cycle (BLC) into three stages: manufacturing, use, and demolition according to the result analysis. In addition, a durability improvement and carbon reduction scheme of "partition, resistance, and repair" is proposed, and the carbon emission reduction index of effectiveness index is proposed. The proposed method is applied to the case of residential buildings in Northwest China. The main conclusions are as follows: the CE of residential buildings are more dependent on the use stage. If the centralized heating system is adopted, the CE in the operation stage account for 80-90%. If the air conditioning refrigeration and heating system is adopted, the CE in the operation stage account for about 50%. Using the method of improving the durability of buildings to extend the service life of buildings is very significant for building carbon reduction (RC); the effectiveness index proposed in this paper includes key indicators such as total CE, service life, and building area. Compared with the traditional index, the effectiveness index is more accurate and comprehensive. CR is the focus of green building, but the impact of economy needs to be considered in practical engineering. In the future research, durability, CE, and economy need to be considered comprehensively for careful study.

Performance evaluation of enhanced clustered latent heat system for air heater using modified organic material

The present work evaluates a new model of clustered latent heat storage unit (LHSU) which specifically designed for air heater. The system involves multi-tank which is arranged in staggered configuration. The clustered system uses direct charge for heating the storage material and employs forced air convection for heat liberation. The maximum temperature increment for the heated air is more than 50 %, showing an effective function of the proposed model. This work also analyzes the role of storage material within the system. The stabilized storage material demonstrates a better performance in term of minimum heat loss on the charge stage. Also, it allows for an excellent charge behavior with average of 3.44 °C/min. The LHSU can be combined with an additional fin for accelerating the operation, making the system can be applied flexibly based on the requirement of the energy system. The operation curve is displayed as battery percentage to understand the characteristics of the system during energy interaction. In general, the addition of fin and modified storage material leads to significant improvement, offering the applicability of the proposed model in various technologies for air heater systems.

Thermal performance of an economical air heater for space heating using composite energy storage materials

ABSTRACT Energy storage materials have the potential to improve the performance of thermal systems due to their excellent thermo-physical properties. Different energy storage materials have been tested for different thermal systems and found adequate to improve their thermal performance. Present work focuses, (i) on the development of two different composite energy storage materials (CESM) by mixing graphite black powder (obtained from lithium batteries cells) in paraffin wax and coconut oil, and (ii) testing of these materials for solar space heating inside the two similar air heating systems namely, Model-2 and Model-3. Air heating trials have been conducted on four different configurations by placing CESM-filled containers on the absorber of the tested heaters. Results of natural and forced convective operations have been compared with a similar conventional air heater (Model-1) and also to some other relevant works on air heating systems. Results revealed that Model-3 is the best model. For this system, improved heat transfer was observed at 356.20 W/m2.K, thermal efficiency was observed at about 78.8%, overall heat loss was computed at 5.91 W/m2.K and maximum exhaust air temperature was observed at about 322.05 K. The cost of Model-3 was about $51.14 (₹ 4110 in Indian currency). Model-3 can be easily developed and used for air heating and drying operations under mild cold climate conditions.

Use of an Air Heating System at the Inlet to the Gas-Turbine Compressor as an Element of the Heat-Recovery System in a Combined-Cycle Power Plant

Use of an Air Heating System at the Inlet to the Gas-Turbine Compressor as an Element of the Heat-Recovery System in a Combined-Cycle Power Plant

Effective thermal performance assessment for prismatic triangular solar air heater integrated with fins and turbulators

A numerical study was conducted to explore the effective usability of prismatic triangular channel solar air heaters integrated with longitudinal fins and quadrilateral rib turbulators. Using the matrix inversion technique and MATLAB-developed code, the governing equations of the system were solved. The analytical model is confirmed, showing commendable agreement with an average discrepancy of 4.2%. For the constant value of quadrilateral rib conditions, the first law and the thermohydraulic performance of the novel air heating system are analyzed by considering the design and operating conditions of Reynolds number, fin height ratio, fin thickness ratio, and number of fins. The achieved results reveal that the provision of fins with rectangular rib roughness enhances the thermal and effective thermal performance by optimizing fin design parameters, leading to a maximum value of 85.48% and 78.58%, respectively. The comparison results reveal that the present work improves the effective thermal performance by 5.14% to 20.2% up to the Reynolds number of 21600. It is an attractive design, achieving a rise in temperature parameter up to 0.012 W/m2K.

Information entropy analysis of the relation between climate and thermal adaptation: A case study in hot summer and cold winter region of China

The shift of paradigm from reductionist to holism in the field of thermal adaptation promoted a boom in thermal adaptation theory and provided a systemic perspective on this issue. The thermal adaptation theory confronts twin difficulties of scale and complexity. The complexity and entropy of occupants' thermal adaptation emerging. This paper aims to investigate the information entropy exchange in the coupled climate-building-occupants system. First, we justified that the building-occupants system is an open system and exchanges energy, matter, and entropy with its surrounding climate system. Then, correlation analysis results suggested that climate entropy could influence thermal adaptation entropy. Thermal adaptation entropy fluctuated with climate entropy and the difference varied between −0.5 and 0.5 below 31 °C. A generalized entropy balance model was proposed for quantifying the entropy exchange among coupled climate-building-occupants systems for both free-running and air-conditioning buildings. The quantitative relation between the entropy of thermal adaptation and H_DTR reveals the dynamic occupant's thermal adaptation under the process of entropy exchange with the climate system. The H_DTR and entropy relation models provide a new perspective on thermal adaptation coupled with climate beyond outdoor daily mean temperatures. Control strategies that integrate the dynamic characteristics of DTR can bring more economical, energy-efficient and comfortable effects to the operation of air conditioning or heating systems. Our findings shed some light on the dynamical and complex thermal adaptation. In further studies, more results and methods from meteorological research could be used for thermal adaptation research and interdisciplinary theories could be adopted to help us better understand occupants' thermal adaptation.

Evaluation of two-stage humidification-dehumidification desalination systems operated by a modified heat pump

The humidification-dehumidification desalination system operated by a heat pump is ideal for the decentralized small-scale desalination plant, due to its advantages of low investment and stable freshwater provision. To overcome the heat source limitation of multi-stage humidification-dehumidification system, a modified heat pump with a subcooler is used to operate the two-stage humidification-dehumidification system. With the difference of heated object, two layouts of the heat pump operated two-stage humidification-dehumidification systems are proposed, which are twice water-heated system and twice air-heated system. A parametric study is conducted to analyze the effect of feed seawater temperature and water/air mass flow ratio on the thermodynamic and economic performances of the proposed systems. A performance comparison is also carried out to analyze the difference between water heating and air heating, together with advantages over the reported systems. According to the results, it can be concluded that optimal feed seawater temperature and water/air mass flow ratio exist for the proposed systems. The twice water-heated system outperforms the twice air-heated system with the maximum freshwater productivity and gain output ratio of 34.69 kg/h and 7.69, while the lowest specific electricity consumption and freshwater production cost of 89.18 kWh/m3 and 14.52 $/m3. These results are also superior to those of previously reported HP-HDH systems, fully demonstrating the value of research and development for this novel system and its promising market application prospects.

Experimental studies on solar reusable can air heating system integrated with latent heat storage

Experimental studies on solar reusable can air heating system integrated with latent heat storage

FABRICATION OF THERMAL BIO-INSULATOR FROM OIL PALM TRUNK FIBER: ANALYSIS OF THERMAL, PHYSICAL AND MECHANICAL PROPERTIES

The majority of air conditioning systems, including both cooling and heating systems, consume a significant amount of electrical energy as a result of their high electrical consumption and prolonged periods of operation. The use of thermal insulation materials in the building can help conserve electrical energy used for room conditioning systems. Natural fibers are used as an alternative in the production of thermal insulation, which is commonly referred to as bio-insulators. The utilization of oil palm trunk (OPT) fiber as the primary material for thermal insulation shows promise. This study aims to determine the specific attributes of OPT fiberboard that make it suitable for use as a thermal bio-insulator. The features examined encompass physical, mechanical, thermal, and fire-resistant attributes. The OPT fiber underwent a treatment process involving boiling at a temperature of 80℃ for a duration of 30 minutes. The fiberboard is manufactured using epoxy adhesive and calcium carbonate additive, and then printed using the hand lay-up process and cold-compaction technique. The physical characteristics of fiberboard indicate that there is a direct relationship between its density and water absorption. Testing revealed that fiberboard has a low thermal conductivity and high heat capacity value. By including calcium carbonate, the burning time of the fiberboard was tested and seen to decrease, indicating a delay in the fiberboard burning process, as evidenced by the extended flame suppression time. The density of OPT fiberboard varies between 0.48 and 0.70 gr/cm3. The absorbency of water is inversely related to its density. Water absorption capacity generally rises with decreased density. The obtained heat capacity value is 1.28-2.38 J⁄(g℃). The mechanical value ranges from 1.00 to 3.55 MPa. The incorporation of calcium carbonate significantly impacts the thermal and mechanical characteristics of the fiberboard. The produced OPT fiberboard satisfies the requirements for good thermal, physical, and mechanical characteristics, making it a suitable bio-insulation material for buildings.

Outdoor performance investigation of a thermoelectric cooler-integrated solar air heating collector

Solar air heating systems are continuously being improved by combining them with other energy conversion technologies. In this paper, outdoor tests were carried out on a thermoelectric heat-pumping solar air heater (TE-SAH), with four (04) TECs (TEC1–12706) attached to the backside of the absorber plate, and powered by a 40Wp mono-Si PV module to pump heat from the absorber plate into the heated air. The thermal energy production, energy efficiency, heat loss coefficients, and heat removal factor were evaluated and compared with a reference system without TECs. The heat collection and energy efficiency of the solar air heater were improved by 7.14 % and 66.71 %, respectively, with the integration of TECs. Heat losses also decreased by 0.46 MJ. Furthermore, the estimated heat removal factor for the TE-SAH was 0.55, higher than 0.49 obtained for the reference SAH. These results showed that PV-TE heat-pumping is a viable means of improving the thermal performance of solar air heaters.

Critical analysis of the energy and exergy performance of an air heater duct with perforated 60-degree V-down baffles affixed to the heated surface

The indirect-mode solar dryer, with a solar air heater as a vital component, is commonly preferred for enhancing agricultural product quality. Energy and exergy analyses for an air heating system assess thermal gain and irreversibility in energy conversion. According to the literature, the easiest way to enhance the SAH’s energy and exergy performance is by incorporating flow-modifying elements or turbulators in the air passage. And the effective-energy assessment accounts for the increased airflow pumping power demands. This work aims to experimentally compare the energy and exergy performance of a smooth air heater duct with one integrated with perforated V-shaped baffles while critically examining the factors leading to the efficiency variations. The racetrack-shaped perforated V-baffles with 60-degree air attack angles are installed on the heated surface with V-down and staggered hole arrays, covering a turbulent flow Reynolds number (Re) range of 5400–13,100 during experimentation. The investigation involves varying the pitch-to-duct depth ratio (p/H) of baffles (with values of 1, 2 and 3) and considering two different hole-aspect ratio (w/d) values of 5.04 and 2.68, with the same open area ratio. The results reveal that baffles with w/d of 2.68 at p/H of 3, causing enhanced airflow turbulence and momentum diffusivity, provide the highest effective-energy ([Formula: see text]) and exergy ([Formula: see text]) efficiencies values of 88.7% and 12.44%, respectively, at Re of 11,816 and 8765. Based on the operating and geometrical parameters used in the experiments, the correlations of [Formula: see text] and [Formula: see text] developed demonstrate good accuracy. The values for mean absolute error, root mean squared error and R 2 (coefficient of determination) in the correlations, developed using the statistical computing R software, are 0.012427, 0.014837 and 0.9913 for [Formula: see text] and 0.004332, 0.005047 and 0.9557 for [Formula: see text], respectively.

Research on control strategy of rapid preheating for power battery in electric vehicle at low temperatures

Due to cold weather conditions, it is not advisable to use the remaining capacity of the power battery to heat it. Instead, the battery can only be preheated during charging when the battery power is almost consumed up. The traditional positive temperature coefficient (PTC) heating system combines the cockpit air conditioning and heating system with the low-temperature preheating system for the power battery cells. The PTC controller is integrated into the air conditioning control system. However, this integration requires the air conditioning to be activated in order to preheat the power battery. As a result, there is energy waste during the charging process. To address the aforementioned issues, this article proposes a rapid preheating system that utilizes an independent liquid circuit equipped with a high-voltage heater. The system achieves a preheating time of 2000 s for a ternary lithium battery with a capacity of 73kWh and a rated voltage of 770 V. Another important finding is that fluctuations in the current of the battery management system (BMS) occur during the rapid preheating process, leading to uncontrolled battery charging and discharging. The battery rapid preheating control strategy has been redesigned to rapidly heat the battery system by disconnecting the rapid charging relay of the high-voltage circuit, thereby prevents over-discharge and overcharge of the power battery. Experiments have shown that the BMS current increases or decreases in a stepwise manner, as expected by the design. The average temperature of the battery pack during onboard charge module slow charging and direct current fast charging is below 35 °C, and the maximum temperature difference is less than 6 °C. The proposed rapid preheating system and improved battery charging architecture can shorten the charging time and reduce energy consumption. This advancement will open up new possibilities for power battery protection and contribute to the development of lithium-ion batteries for electric vehicles at low temperatures.

BETTER EFFICIENCIES OF SOLAR AIR HEATERS ACHIEVED WITH DIFFERENT AIRFLOWS - A BRIEF REVIEW -

The use of solar air heater systems brings with it the convenience of having hot air at discretion for heating households with quite low prices compared to the use of conventional heating sources. The researchers desire to achieve the highest thermal efficiency of these systems has led to the emergence of different ways of improvement. The present work is focused on the available literature in the field of SAH systems made with different types of air flow. The paper also presents the different designs for the realization of airflow types used by researchers for high efficiency during the years 2017-2021.

Patterns of air temperature changes in air ducts of non-contact air heating or cooling systems

The article is devoted to the study of the patterns of changes in air temperature during its movement in a sheet steel air duct during the operation of non-contact air heating systems, when the temperature of the moving air through the duct is higher than the room air temperature, as well as in the process of non-contact air cooling, when the temperature of the moving air in the duct below the room temperature. Based on the mathematical model of the ongoing physical processes developed in the article, an analytical formula is derived that allows, taking into account the presence of a heat-insulating layer or without it, to determine the patterns of changes in the temperature of moving air through the air duct at a given distance, depending on the thickness of the wall of the air duct and the speed of its movement. A dependence is given that determines the value of the heat transfer coefficient of air moving inside the duct to the inner surface of the duct on the speed, which at a constant flow rate is presented as a dependence of heat transfer on the open cross-sectional area of the duct. An analysis was carried out of the change in temperature of the moving volume of air inside the duct as a result of heat exchange with the surrounding air. A comparative calculation of the change in temperature of air moving in a thermally insulated air duct and in an air duct without thermal insulation was performed. The necessity of carrying out a calculation to determine the patterns of changes in the temperature of moving air inside the air duct when designing air heating systems or air conditioning systems is substantiated. It is concluded that it is necessary to conduct a technical and economic analysis on the feasibility of installing thermal insulation of air ducts made of thin sheet steel.

Thermal comfort and retail sales: A big data analysis of extreme temperature's impact on brick-and-mortar stores

The effect of weather on retail sales has long been of great interest to both the business and academic fields. This study investigated the impact of extreme temperatures on brick-and-mortar retail stores in Seoul, Korea. Using a comprehensive credit card transaction dataset, high-resolution weather data, and a semiparametric model, we found a significant increase in sales during extreme temperature events: 4% during heatwaves exceeding 35 °C and 11% during cold spells below −15 °C. This finding is supported by the thermal comfort hypothesis in retail sales, which suggests that consumers are driven to temperature-controlled indoor environments and are inclined to purchase products that provide thermal comfort, such as hot or cold beverages. As extreme weather events become more frequent owing to climate change, accurate sales forecasting during such conditions becomes crucial for retailers. Insights from our research enable retailers to better predict sales under extreme temperature conditions and to strategize accordingly, such as by highlighting thermal comfort products or ensuring optimal indoor temperatures with efficient air conditioning or heating systems.

Investigation of solar air collectors with concave air duct

In this article study attempts to study the thermal performance of solar air collectors with submersible air ducts and pipes. This study is conducting numerical analysis of the solar collector with pin wings and turbulators to study the effects on the Nusselt number. The paper begins with a numerical analysis of conventional air collectors and compares them with theoretical results. Reynolds numbers range from 2000 to 2500. Next, after the solar collector's performance is evaluated with the bath air with channels, the effects of turbulators of different heights on the Nusselt number are analyzed, followed by the combined effects of pin wings and turbulators. The results are comparable to conventional solar collectors, and suggest that the combined effects of pin wings and turbulators can significantly improve the thermal performance of solar air collectors. The results of this study may contribute to the development of renewable energy-based air conditioning, ventilation and heating systems.

Strategies for maintaining indoor temperature in rural residences in highland pastoral areas

Previous studies on improving indoor thermal environments focus on plain areas. However, the scattered rural residences in highland pastoral areas have special climatic conditions and living habits. This article presents an approach to utilize the abundant renewable energy in the local area to create an indoor thermal environment that residents need. A rural village in Qinghai province of China was taken as the target; we used field investigation and questionnaire survey to explore typical layout. Combined with local building codes, two envelope and two heating systems were proposed to achieve indoor thermal comfort. We also introduce building simulation models and field tests to discover four combinations’ energy-saving effects in maintaining indoor thermal comfort. The average energy-saving rate in the heating season of the four schemes is 89.31%, and the mean temperature is 16.64 °C. The results suggest the heating system has a more significant influence on energy consumption than the enclosure structure, which needs attention under the same budget situation. The solar air heating system has better indoor temperature maintenance effects than the carbon fiber floor heating system. Regarding construction, the prefabricated integrated enclosure structures improve thermal insulation performance significantly.

Analytical study of exergetic efficiency of a solar air heater with C-shape roughness element

This study analytically evaluates the exergetic efficiency of solar air heaters incorporating C-shaped rib roughened absorber plates. Compared to flat plate designs, the proposed geometry significantly enhances energy performance. Optimal roughness parameters for maximizing exergy efficiency are identified, providing design guidelines for improved solar air heater systems. The maximum value of exergy efficiency of the Solar air heater, with C-shaped ribs was obtained as 5.9%.

CFD analysis of thermal fluid dynamic parameters inside an organ pipe: influence of air temperature variations

Organ pipes represent a fluid-dynamic challenge since the time of Bernoulli and Reynolds. A complete and reliable description of the fluid behaviour at the basement of the resonator named the “mouth” of the pipe is still absent. In the context of the design of an air-heating system for the attenuation of the inconsistencies between sounding frequencies of organ pipes, computing efforts were carried out focusing on the fluid-dynamic behaviour of the air at the mouth of the pipe at different temperature conditions. Describing the air dynamic and the heat transfer at the mouth level of the pipe, it would be possible to predict the heating conditions within the pipe resonator, which was the main subject of the project. Multiple points on the pipe organ air blowing scheme were considered for simulation results extraction. Temperature, pressure, and audio measurements were performed and no significant influence of the temperature on those parameters was raised from measurements, rising questions about the effective behaviour of the blowed air at the mouth of the pipe. Simulations were performed to predict both the fluid dynamic and the heat transfer. A finite volume approach in Fluent environment was chosen. The SST k-omega model was considered in reliability vs computation time balance. 3D simulations were performed based on a CAD reconstructed model of a real pipe. The results of the simulations confirmed experimental data, and they may prove the absence of a significant mass exchange between the in and outside of the mouth of the pipe. The oscillation of the air membrane at the mouth of the pipe may be cleared from instabilities and turbulence regime phenomena, as usually described in the literature.

Lay-out of air source heat pump heating system in Lugang Logistics Park

In order to understand the process of using the heat pump heat organization, the author proposes to conduct a study based on the concept of heat pump air heating system in ?Land Port Logistics Park?. The author first analyzed the heating characteristics of the ground transportation fleet according to the actual situation, optimized the design of the heat pump, and proposed the same plan. Second, taking some provincial underground parks as examples, the actual performance of the park?s air source heat pump heating system was tested. According to the test, the temperature difference between the supply and return water is 3-4?C, and the average COP of the entire heating season is only 2.1. Based on the analysis and analysis, the meaning of the problem in the actual operation of the heat pump is explained, the cause of the problem is the determination of the pressure and the design plan. After installation, energy consumption can be further reduced, and it advises on the progress and use of the ventilation system. By using electric equipment to heat the docks in the port, it is possible to meet the heating needs of the park and reduce energy consumption and air pollution. Good this is a green and low carbon promise.