Performance Of Heating System Research Articles

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.

Experimental assessment and 3D numerical simulation of the thermal performance of a direct solar floor heating system installed in a bathroom in Casablanca city, Morocco: parametric, economic, and environmental analysis

Experimental assessment and 3D numerical simulation of the thermal performance of a direct solar floor heating system installed in a bathroom in Casablanca city, Morocco: parametric, economic, and environmental analysis

Deep reinforcement learning for PID parameter tuning in greenhouse HVAC system energy Optimization: A TRNSYS-Python cosimulation approach

The control of indoor temperature in greenhouses is crucial as it directly impacts the crop's thermal comfort and the performance of heating, ventilation, and air-conditioning (HVAC) systems. Conventional feedback controllers, like on/off, can sometimes make HVAC system work at full capacity when only half that capacity is needed. In contrast, the proportional-integral-derivative (PID) controller, provides precise control based on its P, I, and D parameters. However, it lacks a formal design procedure for optimizing a specified objective function. Previous studies have utilized conventional PID tuning approaches to track room setpoint temperature for residential buildings, data centers, and office buildings, with limited research in greenhouse applications. To address this gap, this study proposes a flexible PID controller that employs a deep reinforcement learning (DRL) algorithm to optimize its parameters, by tracking the setpoints and energy consumption of a greenhouse planted with tomatoes. This approach is different from the typical method of using the trained RL agent directly in HVAC controls. Through a self-made TRNSYS-Python cosimulation framework, the DRL agent interacts directly and in real time with the greenhouse and its plants. Consequently, optimized PID parameters were established and tested in the simulated environment. The resulting performance, in terms of both energy consumption and its ability to maintain the crop’s comfort temperature, was compared with the simulated on/off and manually tuned PID controllers. Compared to the on/off baseline control, the proposed PID optimized parameters reduce energy use by 8.81% to 12.99% and the manually tuned PID parameters with the Ziegler-Nichols tuning method reduce energy use by 7.17 %. Additionally, the proposed method had a deviation of 2.07% to 3.13%, while the manually tuned PID controller and the on/off controller had deviations of 7.27% and 3.27%, respectively, from the minimum comfortable temperature. This study serves as a framework for improving the energy efficiency of greenhouse HVAC system operations.

Experimental and theoretical investigation on a novel solar-assisted absorption-resorption heat pump (ARHP) system towards clean heating

Among thermally-activated heat pumps, absorption-resorption heat pump (ARHP) is dominant by the ability of combining with low-temperature heat for efficient space heating. In this work, an ARHP experimental prototype is developed based on the previous thermodynamic cycle and tested to obtain the operation details such as coefficient of performance (COP), supply water temperature, heating capacity and so on. The experimental and the previous theoretical results are compared and mutually verified. The exact performance of the solar-assisted ARHP heating system is then investigated and compared with that of the conventional vapor compression heat pump (VCHP) in terms of primary energy ratio (PER) and primary energy saving ratio (PESR). The experimental results show that the COP increases greatly from 1.125 to 1.353 when the heat source temperature increases from 90 °C to 150 °C at the ambient temperature and return water temperature of 0 °C and 30 °C, respectively. Under given conditions, the measured heating capacity reaches a maximum value of 18.5 kW, 9.0 % lower than the rated value. The theoretical results reveal that solar fraction above 30 % can make PER of the solar-assisted ARHP heating system comprehensively greater than that of the reference VCHP system. Optimal solar contribution to space heating can be achieved based on the proposed ARHP if solar heat is dividedly utilized in its temperature zones of 10–35 °C, 35–83 °C and above 83 °C.

Assessing performance of an external compound parabolic concentrator solar collector with cascaded latent heat thermal storage

AbstractThis study presents quantitative results of charging experiments conducted on cascaded thermal energy storage system (CTESS) integrated with external compound parabolic concentrator solar collector (XCPCSC). Increasing mass flow rate in 2‐stage CTESS integrated with XCPCSC resulted in a 30% reduction in initiation time of phase change materials (PCMs) during charging, with a higher mass flow rate of 0.025 kg/s. However, due to disparate melting point temperatures of PCMs, phase transition in the two‐stage CTESS did not occur simultaneously, leading to poor heat transfer rates within the CTESS. To address this, study extended number of phases from two to three, resulting in a 1.5‐fold increase in rate of heat transfer compared to 2‐stage PCM system. The simultaneous melting processes at various stages in the CTESS maximized energy absorption, leading to a 25% increase in system efficiency. Notably, the values of energy stored efficiency and over‐all efficiency reached their peak values of 95% and 60%, respectively, between t = 12.00 h and t = 13.00 h. This time period also saw a significant increase in collector efficiency to 72%. These quantitative findings highlight importance of mass flow rate and PCM arrangement in achieving efficient heat transfer and system performance in a CTESS integrated with XCPCSC.

Research on optimization of the heating system in buildings in cold regions by energy-saving control

Building heating is an indispensable part of people's winter life in cold regions, but energy conservation and emission reduction should also be taken into account during the heating process. This paper provides a concise overview of the heating system based on air-source heat pump radiant floor and its control strategy. It also optimizes a control system based on thermal comfort and energy efficiency ratio, and analyzes a room in Xining City, Qinghai Province, to test the heating system performance under two control strategies. The final results show that under the traditional control strategy, the cumulative working time of the heating system within a day was 15 hours, the average indoor temperature was 17.36℃, the temperature standard deviation was 2.08℃, and the average power consumption was 189.6 kWh. Under the improved control strategy, the cumulative working time of the heating system within a day was reduced to 10 hours, the average indoor temperature was 18.56℃, the temperature standard deviation was 0.92℃, and the average power consumption was 132.5 kWh.

Investigation of magneto-convection characteristics in a sudden expanding channel with convex surface geometry under thermally developing flow conditions

PurposeThe purpose of this study is to analyse the magnetic field effect on Fe3O4/H2O Ferrofluid flowing in a sudden expansion tube, which has specific behaviour in terms of rheology, with convex dimple fins. Because the investigation of flow separation is a prominent application in performance, the effect of magnetic field and convex dimple on the thermo-hydraulic performance of sudden expansion tube are examined, in detail.Design/methodology/approachDuring the solution of the boundary conditions of the sudden expansion tube, finite volume method was used. Analyses have been conducted considering the single-phase solution, steady-state, incompressible fluid and no-slip condition of the wall under forced convection conditions. In the analyses, it has been assumed that the flow was developing thermally and has been fully developed hydrodynamically.FindingsThe present study focuses on exploring the influence of the magnetic field, nanofluid concentration and convex dimple fins on the thermo-hydraulic performance of sudden expansion tube. The results indicate that the strength of the magnetic field, nanofluid concentration and convex dimple fins have a positive effect on the convective heat transfer in the system.Originality/valueThe authors conducted numerical studies, determining through a literature search that no one had yet investigated enhancing heat transfer on a sudden expansion tube using combinations of magnetic fields, nanofluids and convex dimple fins. The results of the numerical analyses provide valuable information about the improvement of heat transfer and system performance in electronic device cooling and heat exchangers.

Seasonal field study on thermal comfort in university classrooms in Mediterranean climate

The assessment of indoor environmental conditions of educational buildings is not only essential to ensure the correct performance of heating, cooling and ventilation systems but it is also fundamental to guarantee a suitable environment. This study aims to analyse the thermal comfort of students in teaching–learning spaces in university buildings with natural ventilation. A field measurement campaign and a questionnaire survey were carried out from September 2021 to June 2022 in educational buildings in southern Spain. The collected data were analysed and the neutral temperature in each season was obtained, based on the thermal sensation votes of 1966. The neutral temperatures found in this study were 23.5°C, 23.1°C, 23.3°C and 23.9°C, for autumn, winter, spring and summer, respectively. The ranges obtained for 90% acceptability in the winter season (21.1°C–25.1°C) provided lower temperature limits than the ranges obtained in the summer months (22.6°C–25.3°C). The highest values for clothing insulation were found in the autumn (0.90 clo) and winter (0.75 clo) seasons, compared to the spring (0.5 clo) and summer (0.4 clo) seasons. An adaptive thermal comfort model was applied. These findings could be used to improve thermal comfort and to optimise energy consumption according to the students’ actual thermal perception.

Influence of °Brix/Acid, and flow rate of pineapple juice and electric field strength on the performance of continuous ohmic heating system.

The online version contains supplementary material available at 10.1007/s13197-024-05961-x.

A Numerical Study to Improve the Efficiency of Solar Collector used for water heating using Phase Change Material

Solar water heaters are an effective technology for harnessing renewable solar energy to provide hot water for households and businesses. However, their efficiency can be impacted by factors like intermittent sunshine, heat losses, and low radiation intensity. The aim of this study is to increase the efficiency of solar water heaters through the use of phase change materials (PCMs). PCMs have the ability to store latent heat during phase change, releasing it later when needed. This study uses numerical simulations to analyze the effect of integrating different PCMs into a flat plate solar collector design. The findings could then be validated experimentally and applied to improve the real-world performance of solar water heating systems. The PCMs are placed inside the collector to absorb heat during the day and release it after sunset to continue heating the water. The research seeks to determine the optimal PCM properties, structure, and placement within the collector to maximize heat storage and transfer. The efficiency and performance of the solar collector system with different PCM configurations have been compared to those of a conventional collector without PCM. The outcomes uncover that the use of suitable PCMs can significantly improve the efficiency and heat output of the solar collector, especially during periods of low radiation and after sunset. The optimal PCM configuration maintains higher water temperatures for longer, allowing solar water heating to continue into the evening. The results may provide valuable insights for using PCMs to boost the efficiency of solar thermal technologies

Research progress of direct contact heat storage based on phase change heat storage

AbstractPhase change heat storage presents a promising solution to address challenges related to new energy intermittency and waste heat recovery. However, for it to function as an effective energy hub, heat storage becomes crucial. Among the available options, the direct contact heat accumulator stands out due to its simple structure, substantial heat transfer area, and minimal heat transfer resistance, making it a favorable choice for enhancing energy storage rates. Although a great deal of research has been done on phase change materials and heat accumulators over the years, a systematic review of direct‐contact heat accumulators is lacking. This article reviews the related research on direct contact heat storage, aiming to summarize the research work on direct contact phase change heat storage systems. Various phase change materials (PCMs) for direct contact systems are analyzed, and the study of PCM melting crystallization behavior, heat transfer coefficients and system performance in direct contact systems is summarized, as well as the improvement methods for direct contact vessels and PCMs. It provides a useful reference for future research on direct‐contact heat storage systems.

Radiation-convective heat transfer and performance analysis of a parallel-plates duct direct absorption solar heat collection system

Solar photo-thermal conversion and solar heat collection are hot topics today. However, which solar collection mode is the best? The question has puzzled scholars for many years. In this study, a direct absorption solar heat collection (DASC) duct system was investigated. Carbon quantum dots (CQDs) were selected as the heat absorption medium. Different absorption modes were clarified. It is found that the ratio of the radiation penetration depth of nanofluids to duct depth (duct penetration ratio, α) plays a key role in the duct heat transfer and system performance. Totally three solar heat collection modes can be classified depending on the value of α: volume absorption (partial volume 0<α<1 or whole volume α = 1), surface absorption (upper α → 0 or bottom α → ∞) and hybrid absorption for α > 1. Of them, the whole volume absorption has the best performance when α = 1, while the hybrid performs the best when the penetration ratio is not unity. Surprisingly, a higher fluid absorption coefficient does not necessarily lead to a higher photo-thermal performance. The extreme high fluid absorption coefficients (upper surface mode) are inferior to extreme low absorption coefficients (bottom surface mode). Of the different modes, the total Nusselt numbers in the whole volume absorption mode are 2–3 times higher than those in the bottom surface absorption mode. For solar heat collection, convective heat collection is better than standstill collection, and a certain flow velocity should be ensured to have a satisfactory efficiency. The findings were experimentally verified.

DEVELOPMENT AND INSTALLATION OF SOLAR WATER HEATING SYSTEM FOR FEDPODAM HOSTEL

This paper presents the result of the Development, Installation and Performance evaluation of a 500 liter capacity hot water storage tank with an additional 500 liter capacity cold water storage tank that was, developed, installed and tested at Maryam Abatcha female hostel in the Federal Polytechnic Damaturu, Yobe State, Nigeria which is located at latitude 12.290N and Longitude 11.440E using available materials and thermo syphon principle at an average solar radiation of 630W/m2 to investigate the potential of using solar either directly and indirectly for heating water and to compare its cost with electricity. This design utilized a flat plate collector which was chosen because of the simplicity in construction and ease of maintenance. Two collectors of 1m2 each with single glazing were used as a heat exchanger. The surfaces of the collectors were painted with black paint of absorptivity 0.95 and emissivity of 0.09 to improve its absorption capacity. Readings were taken for a period of nine months starting from March, April, May, June, July, August, September, October and November with minimum ambient temperature of 320C. Maximum hot water temperature inside the tank as 82.30C with an average efficiency of 28.06% in June, with clear sunny atmosphere days and November with lower outlet likely due to cold dusty of the period. Test conducted reveal that the system could satisfy the hot /warm water requirements of the hostel. It was also observed that the water temperature is a function of solar radiation while the cloud cover and dust particles were observed to also affect the performance of solar water heating system thereby reducing its efficiency.

Experimental and simulation study on a zeotropic ORC system using R1234ze(E)/R245fa as working fluid

Organic Rankine Cycle (ORC) is a highly promising technology for converting heat to power, which has a widespread application in renewable energy utilization and waste heat recovery. Zeotropic working fluids are widely investigated to enhance the performance of ORC. In the present study, an experimental study on zeotropic mixture R1234ze(E)/R245fa is conducted under specified operating conditions and the operating behaviors of the ORC system are evaluated. An ORC simulation model (BP-ORC) based on a back propagation neural network and heat exchanger simulation modules is developed. The contribution factors that trigger the differences in heat transfer and system performance among the various working fluids are investigated. The operating behaviors of the heat exchangers and system are simulated for the working conditions beyond the experimental study. R1234ze(E)/R245fa (0.25:0.75 and 0.50:0.50) features a wider operating range of mass flowrate than R245fa due to their relatively lower density. The net power output of R1234ze(E)/R245fa (0.50:0.50) is 4.63 % higher than that of R245fa at a mass flow rate of 0.164 kg/s due to its relatively higher heat transfer performance. The variation of density and operating pressure plays a significant role in influencing the heat transfer behaviors and system performances.

Impact of Building Automation on Indoor Air Quality and HVAC Performance

In response to the growing emphasis on healthier indoor environments and sustainable building practices, this research delves into the intricate relationship between building automation and key facets of indoor environmental quality. Specifically, the study focuses on the impact of building automation systems on Indoor Air Quality (IAQ) and the overall performance of Heating, Ventilation, and Air Conditioning (HVAC) systems. With the increasing demand for enhanced IAQ, building automation emerges as a crucial tool for real-time monitoring and optimization of various IAQ parameters. The research explores the comprehensive integration of automation technologies within building systems, elucidating their multifaceted effects on IAQ. By scrutinizing the intricate interplay between automation systems and HVAC components, the study unveils the ways in which automation technology influences and contributes to IAQ management. The investigation encompasses a thorough examination of sensor technologies, control algorithms, and data analytics employed in building automation to ensure a nuanced understanding of their impact on IAQ. Furthermore, the study elucidates the broader implications of building automation on HVAC system performance. It investigates how automated control mechanisms, coupled with real-time data analytics, contribute to the efficient operation of HVAC systems in maintaining optimal IAQ. The research contemplates the synergies between automation technologies and HVAC components, emphasizing their role in not only ensuring healthier indoor environments but also in achieving energy-efficient and sustainable HVAC operation.

Numerical Simulation of Heat Transfer through Uniform Multilayer Walls using ANSYS

The paper presents a study on modelling the main heat transfer parameters through opaque building elements. The need for models to assess the thermal behavior of a building has increased greatly in recent years, primarily to allow a more accurate determination of the energy consumption of buildings to evaluate the performance of heating systems. In recent times, mathematical models and software have been implemented to obtain simulations that are very close to the real functioning of the main components of buildings. The present article consists in modeling a multi-layer homogeneous wall, which separates the interior space of an enclosure (rooms) from the outside environment. The article aims to carry out a series of simulations on the structure of a non-homogeneous multilayer wall using the ANSYS program. The simulations have been performed highlight how the values vary (both numerically and graphically) for a series of characteristic parameters such as heat fluxes, temperatures, convection coefficients. The values of the parameters obtained with the ANSYS program were also compared with those obtained by classical numerical calculations.

A comprehensive comparison study on household solar-assisted heating system performance in the hot summer and cold winter zone in China

Distributed solar heating systems have high energy-saving potential as clean and energy-efficient production units in residential building applications. Solar energy resources are weak in hot summer and cold winter zone in China, which makes it difficult to completely rely on solar energy to heat residential buildings. A critical challenge is the lack of a theoretical basis for how to choose the solar-assisted heating system form. In this paper, seven solar-assisted heating systems are modeled and their performances are evaluated in six cities by using TRNSYS software. In terms of performance indicators, the solar fraction, the season performance factor, and the heat efficiency are used to thoroughly discuss the viability of using solar heating technologies in this zone. Based on the results, the average indoor air temperature was maintained between 16 °C and 20 °C, and the lowest solar fraction obtained was 10.1%. The carbon emission reduction in each city ranged from 60 kg to 400 kg, yielding good environmental benefits. According to the comprehensive comparison of the six evaluation indexes considered, the parallel or dual-source solar-assisted air source heat pump system can be used in a zone with medium solar energy resources. It is more suitable to use a dual-source solar-assisted air-source heat pump system in a zone with poor solar energy resources. The findings of this work can guide and promote the widespread application of distributed solar heating in household residential buildings in the hot summer and cold winter zone in China.

Entropy weighted WASPAS and MACBETH approaches for optimizing the performance of solar water heating system

In this work, multi-criteria decision-making (MCDM) techniques namely the weighted aggregated sum product assessment (WASPAS) method and the measuring attractiveness by a categorical based evaluation technique (MACBETH) are applied for predicting the optimum performance of a solar water heating system (SWHS) equipped with perforated delta-shaped obstacles. In total fifteen SWHS design alternatives based on the variation of pitch ratio (0.5, 1, 1.5, 2.0), angle of attack (15°, 30°, 45°), and Reynolds number (400, 800, 1200) were selected. The Nusselt number, friction factor, and thermohydraulic efficiency were fixed as the selection criteria in evaluating SWHS alternatives. By the entropy method, the importance of the identified criteria is quantified as weight, whereas the ranking of SWHS alternatives is determined by the WASPAS and MACBETH methods. The results show that the SWHS design alternative with a Reynolds number of 1200, pitch ratio of 1, and 45° angle of attack exhibits the optimal performance in selected criteria. Sensitivity analysis was used to demonstrate the robustness of the acquired ranking findings, which were further, validated using ten popular decision-making models.

Experimental study on solar heating system based on heat pipe technology for mitigating subgrade frost heave

Subgrade frost heave is the main reason that affects the safe operation and comfort of trains during the cold season. Solar heating system based on heat pipe technology is a promising method to mitigate the frost heave by raising the subgrade temperature. In this paper, a field experiment was conducted to evaluate the heating performance of the solar heating system based on heat pipe technology in the cold season. In addition, the heat collection performance and stability of the system are compared with other solar heating systems. Finally, its applicability is discussed. Experimental results revealed that the solar heating system based on heat pipe technology can effectively raising the soil temperature and mitigate the frost heave of subgrade. During the experiment period, the soil temperature at the depth of −0.5 m in the experiment site was 5 °C higher than that of the comparison site, and the maximum freezing depth was 0.4 m, which was 56 % lower than that of the comparison site. The mean daily temperature of heat collection units (HCUs)fluctuated around 30 °C, and the mean daily temperature of the two-phase closed thermosyphons (TPCTs) fluctuated between 15 °C and 30 °C. The heat transfer efficiency of System 1 and System 2 is greater than 0.5, and the total effective heat transfer during the experiment period is 512 MJ and 283 MJ, respectively, and the heat transfer difference is about 2 times. Compared with other solar heating systems, the system proposed in this paper has good heat collection performance and more superior system stability. The mean daily heat transfer of System 1 and System 2 is 6.4 MJ and 3.71 MJ, respectively, which is 62.9 % higher and 5.6 % lower than the mean daily heat loss of subgrade of 3.93 MJ, respectively. The system has the application prospect of low maintenance cost and good long-term anti-frost heave effect.

Benchmarking Heating System Performance in Office Buildings through Grey-box Modeling

The transition to renewable energy sources requires that larger shares of heating production should come from heat pumps both on individual level and in district heating networks. The efficiency of heat pumps is highly dependent on the temperature lift. Therefore, it is key to assess the possibilities of low-temperature heating in buildings. This paper proposes a data-driven methodology to analyse and benchmark the performance of radiator heating systems, by estimating parameters for the building’s envelope and heating system using Modelica with ModestPy. The methodology requires little a-priori knowledge and common data sources and provide valuable insights on the potentials of lowered operating temperatures. The methodology was tested on a newly renovated office building in Copenhagen and was able to consistently estimate characteristics of the envelope and capacity of the heating system. By using information on the actual capacity of the heating system, the methodology demonstrated the potential for lowering the heating supply temperatures, thereby reducing heat pump electricity consumption with 9 %.