Low-cost Heat Research Articles

Application of heat pump assisted solar evacuated tube water heater operated within passive solar house in severe cold region

Replace coal with solar energy to low-cost heating in severe cold regions can improve indoor air quality, but indoor thermal comfort is not fully guaranteed. Therefore, a dual-source heat pump (DSHP) assisted solar evacuated tube water heater heating system was used in a house with sunspace to meet the heating stable and cleaning. TRNSYS model verified by experiment was used to research performance and economy of system. Results found the higher ambient temperature and solar radiation, the more heat from sunspace, solar assisted heat pump (SAHP) and solar water heater, conversely, the longer heating time of air-source heat pump (ASHP). During heating season, solar fraction of heating was 51.6 %, solar heat collection efficiency was 46.0 %, EER was 3.35, COP were 2.81 (ASHP) and 3.65 (SAHP). Heating time proportion of ASHP, SAHP and solar water heating were 15.0 %, 40.3 %, 44.7 %, ASHP heating was accounting for 22 % and 50 % in November and January. The system, sunspace supplied 16707.1, 2307.6 kW h of heat for room, solar effective heat collection was 10107.0 kW h, power consumption was 5164.7 kW h, CO2 emission reduction was 14232.4 kg. The dynamic payback period of system was 6.78 years, as will be shortened with support of clean energy heating policy.

Low-cost heat assisted ambient ionization source for mass spectrometry in food and pharmaceutical screening.

Ambient Ionization Mass Spectrometry (AI-MS) techniques have revolutionized analytical chemistry by enabling rapid analysis of samples under atmospheric conditions with minimal to no preparation. In this study, the optimization of a cold atmospheric plasma for the analysis of food and pharmaceutical samples, liquid and solid, using a Heat-Assisted Dielectric Barrier Discharge Ionization (HA-DBDI) source is described. A significant enhancement in analyte signals was observed when a heating element was introduced into the design, potentially allowing for greater sensitivity. Furthermore, the synergy between the inlet temperature of the mass spectrometer and the heating element allows for precise control over the analytical process, leading to improved detection sensitivity and selectivity. Incorporating computational fluid dynamic (CFD) simulations into the study elucidated how heating modifications can influence gas transport properties, thereby facilitating enhanced analyte detection and increased signal intensity. These findings advance the understanding of HA-DBDI technology and provide valuable insights for optimizing AI-MS methodologies for a wide range of applications in food and pharmaceutical analysis.

The Critical Ambient Temperature Threshold for Safe Fan Use in Young Adults During Extreme Heat Exposure

Introduction: The electric fan may be an effective, low-cost heat resilience solution during extreme heat. Fans have been shown to attenuate the rise in cardiovascular and thermal strain relative to still air in young adults, particularly during exposure to more humid conditions. When ambient temperature exceeds skin temperature, a fan improves sweat evaporation from the skin surface, which counterbalances the increased rate of convective heat gain. However, at higher air temperatures, the increased convective heat gain may exceed the rate of evaporative heat loss resulting in net heat gain and increasing physiological strain. The purpose of the present study was to identify the critical ambient temperature limit, where increased physiological strain will be observed, with a fan in comparison to still air. Method: To date, 6 participants (4 females; 24±9 y; 72.8±17.8 kg; 1.8±0.2 m) have completed two 180-minute temperature ramp heat-exposures (37°C to 47°C at ~0.05°C/min, 25%RH) on separate days. Wearing standardized t-shirts and shorts, the participants remained seated while either i) facing an electric fan (5.3±0.9 m/s) or ii) in still air (0.1±0.0 m/s). Rectal and skin temperature, heart rate, blood pressure, whole-body sweat loss, thermal comfort, and thermal sensation were measured every 10 minutes. Results: Rectal temperature was similar between fan and still air up to 43°C (P>0.92), however was greater with a fan from 44°C onwards (p<0.05). Skin temperature was higher with a fan compared to still air throughout the exposure (p<0.001). Heart rate was similar between fan and still air until 44°C (P>0.61), after which heart rate was higher with a fan (p<0.05). Mean arterial pressure was not different between fan and still air at any air temperature (P=0.53). The rate pressure product was higher with a fan compared to still air when the ambient temperature exceeded 44°C (p<0.05). Whole-body sweat losses were greater with a fan (1215±250 g) compared to still air (675±103 g, P=0.006). No differences between fan and still air were observed for thermal comfort (P=0.22) or thermal sensation (P=0.73) throughout the temperature ramp protocol. Conclusion: When ambient temperature exceeds 43°C, electric fan use results in greater physiological strain at rest in young healthy adults relative to still air. This research was supported by Dr. Ravanelli’s Natural Sciences and Engineering Research Council of Canada Discovery Grant (PIN#2022-05096). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Dynamic performance forecast analysis of MHP-PV/T-IDXSAHP system during heating season

MHP-PV/T is a novel PV/T with phase change heat transfer, uniform flow of working medium and good anti-freeze performance. The excellent year-round performance of MHP-PV/T has been demonstrated in previous studies and is more suitable for winter heating in northern China. In this work, we further combine MHP-PV/T with dual source heat pump to form an experimentally validated indirect expansion-solar assisted heat pump (IDX-SAHP) system and simulates the overall performance of the heating system in winter based on TRNSYS in Lanzhou, China. The component type50b of TRNSYS was modified to make it closer to the actual results of MHP-PV/T. Research shown that the thermal efficiency of MHP-PV/T heat pump system can be maintained well throughout the heating season at the SAHP/ASHP switching temperature is 7 ℃ in winter. The net system energy efficiency ratio (NSEER) during heating season is range from 3.28 to 5.42, which can achieve highly efficient and low cost heating. For this system, the photovoltaic power generation is sufficient to meet the operation of three water pumps. By connecting surplus electricity to the grid, a total of 1806.25 ¥ of electricity revenue can be obtained around the year. The PEUR of the system is 72.26 %, the DPP taking 5.133 years, and the annual CO2 emission reduction is 13486.5 kg. Significant energy, economic, and environmental benefits of the system. This study demonstrates the application prospects of PV/T heat pumps and provides a reference basis for subsequent research on MHP-PV/T heat pump systems in cold regions.

Replacing All Fossil Fuels With Nuclear-Enabled Hydrogen, Cellulosic Hydrocarbon Biofuels, and Dispatchable Electricity

Abstract We describe a roadmap using three sets of technologies to enable base-load nuclear reactors to replace all fossil fuels in a low-carbon world. The technologies integrate nuclear, wind, solar, hydroelectricity and biomass energy sources. Base-load nuclear reactors with large-scale heat storage enable dispatchable electricity to the grid. The low-cost heat storage enables buying excess wind and solar electricity to charge heat storage for later electricity production while providing assured generating capacity. Nuclear hydrogen production facilities at the scale of global oil refineries produce hydrogen to replace natural gas (gaseous fuel) as a chemical feedstock and heat source. Single sites may have tens of modular reactors produced in a local factory to lower costs by converting to a manufacturing model for reactor construction. Nuclear heat and hydrogen convert cellulosic biomass into drop-in liquid hydrocarbon biofuels to replace fossil-fuel gasoline, diesel, jet fuel, and hydrocarbon feed stocks for the chemical industry. External heat and hydrogen inputs increase the quantities of biofuels that can be produced per unit of cellulosic feedstock, thus assuring sufficient biomass feed stocks to replace all crude oil without major impacts on food and fiber prices. The biofuel production system enables the removal of large quantities of carbon dioxide from the atmosphere that is sequestered as carbon char in the soil while recycling plant nutrients (potassium, phosphorous, etc.) to assure agricultural and forest sustainability.

Square solar updraft tower coupled phase change material: An experiment

Solar updraft tower is a low-cost heat collection ventilation power generation technology in solar heat utilization technology, which has high research potential and application value. However, the traditional circular solar updraft tower has some problems, such as low thermal efficiency, short working time, and unstable heat collection performance, which are caused by ambient crosswind disturbance and low heat capacity of the absorber. Therefore, this study designed a new square one-sided inlet solar updraft tower to prevent most of the heat from being lost through the ambient crosswind. At the same time, a phase change paraffin thermal storage unit was coupled in the absorber, which could reduce the temperature field fluctuation of the device and extend the working time by releasing latent heat when the solar irradiance decreased. Control experiments were conducted on the two processes. The test results show that the working time of the coupled new device is at least one hour longer than that of the square solar updraft tower without phase change material. The average temperature difference between the inlet and the external environment after the solar radiation drops at 17:00 is 79.12% higher than that of the traditional circular solar updraft tower of the same size, and the average instantaneous heat collection efficiency is 99.98% higher. While the effectiveness of the improved solar updraft tower is proved, the economic analysis of the integrated application of the single-side inlet solar updraft tower on the agricultural solar greenhouse is made. The carbon emission reduction of at least 2.144 tons in the year of using this system, and the construction cost is saved about 1330USD. The use of the system will reduce carbon emissions by at least 2.144 tons per year, save at least 2.30 tons of standard coal, and save construction costs of about 1330 US dollars. The research can provide theoretical and technical support for the efficient commercial application of solar updraft towers.

Research on the day-ahead scheduling optimization method of medium-depth geothermal cascade heating system

The medium-depth geothermal cascade utilization technology plays a crucial role in achieving low-carbon and low-cost heat supply. However, the traditional rigid regulation method faces challenges in ensuring real-time supply-demand balance due to the district heating demand being influenced by outdoor weather and the complexity of the operating parameters of the medium-depth geothermal cascade heating system. Consequently, problems such as low utilization of geothermal water and high operating costs arise. To address these issues, this study proposes a day-ahead scheduling optimization method for the medium-depth geothermal cascade heating system, integrating the adaptive moment estimation (Adam) optimized long short-term memory (LSTM) prediction algorithm, interior point method, and particle swarm optimization (PSO) algorithm. Based on enhanced precision prediction, this study aims to optimize variables including partial load rate (PLR), flow rate, cooling water return temperature, and chilled water return temperature. The effectiveness of the proposed optimization method is verified through the establishment of a TRNSYS simulation platform in conjunction with MATLAB, focusing on a geothermal cascade heating project in Tianjin. The results demonstrate that the proposed day-ahead scheduling optimization method effectively promotes the coordinated operation among energy systems, achieving significant energy savings for the energy station (10.13 %). The novelty of this research lies in the utilization of scientific algorithms to optimize multiple variables within the system, which holds the potential to enhance the matching of supply and demand and improve the operational effectiveness of comparable systems. In summary, this study provides valuable insights and practical implications for the field of strategic optimization. However, it is essential to acknowledge that the applicability of the findings to other geographic locations, different scale projects, or varying system configurations necessitates additional investigation. The generalizability is subject to further research and exploration.

Dynamically distributed district heating for an existing system

The study in hand introduces the concept of dynamically distributed district heating. The concept addresses the challenges related to transforming an existing 3rd generation district heating system into a 4th generation system, one area at a time. It enables a cost-efficient option for introducing low-temperature distribution and new distributed heat supply while preserving the advantages of an efficient, more centralised system. The concept includes new large-scale heat storage capacity in areas on the outskirts of the network or within otherwise suitable locations, charged during summer when low-cost heat is commonly available. These areas also have new distributed heat supply. The areas are run in an island-mode during the heating season, i.e. disconnected from the main system. The study presents a preliminary analysis of the concept using Helsinki district heating system as a case study based on open data on district heating demand, building stock data and optimisation modelling of the district heating system for assessing the heat supply costs.

Fire hazard of epoxy-based transparent wood

Transparent wood is a modern bio-renewable material with great potential for both science and industrial applications. However, the fire hazard of transparent wood is still almost unexplored. This study aims to investigate the impact of pristine basswood modification to epoxy-based transparent wood on the fire hazard and to train neural networks for the prediction of heat release rate from mass loss rate of pristine basswood, epoxy-based transparent wood, and epoxy resin. Transparent wood was prepared by lignin modification in pristine small-leaved basswood (Tilia cordata Mill.) and subsequent vacuum infiltration by epoxy resin. The fire hazard of the samples was determined by the cone calorimeter at four heat fluxes of 20–50 kW m−2. The fire hazard of investigated materials was compared based on the critical heat flux, ignition temperature, heat release rate, effective heat of combustion and time to flashover. Transparent wood showed higher resistance to ignition (higher critical heat flux and ignition temperature) than pristine wood. However, other parameters (heat release rate and effective heat of combustion) were higher (worse) and the time to flashover was lower (worse) for transparent wood than for pristine wood. Trained neural networks for predicting heat release rate from the mass loss rate of wood (both pristine and transparent) and epoxy resin showed coefficients of determination from 0.70 to 0.92. Trained neural networks with a coefficient of determinations above 0.90 are usable for low-cost heat release rate measurements in both science and industrial applications.

The In-House Method of Manufacturing a Low-Cost Heat Pipe with Specified Thermophysical Properties and Geometry

Various types of heat pipes are available to purchase off the shelf, from various manufacturers, but most of them have strictly defined geometry and technical parameters. However, when there is a need to use a heat pipe (HP) with an unusual size and shape or working conditions other than the standard ones, it becomes very costly to order them from manufacturers, especially in small quantities, and only a few producers are willing to fulfill such an order. This paper presents a detailed description and step-by-step method of manufacturing and testing a low-cost HP with specific properties and geometry, cooperating with a modular heat recovery system based on the use of phase change materials (PCM) for electromobility applications. The presented heat pipes were made entirely by hand, primarily with the use of basic workshop tools, without the use of specialized and automated CNC machines. Utensils used during the process were either made by hand or using desktop FDM 3D printers. During the evaluation of heat pipes’ performance within PCM (coconut oil), simple statistical functions were used. One-dimensional and two-dimensional histograms were used to visualize data obtained during this research. The presented method allows the manufacturing of heat pipes that are, on average, able to melt about 35% more PCM than an empty copper pipe with the exact same geometry. The HPs’ performance in coconut oil was evaluated on the basis of their future applications.

A high strength and flexible multilayered thin film laser induced graphene heater for thermal applications

Increasing demand for wearable sensors and heating elements has occurred recently. Herein, graphene has been observed as a biocompatible, cost effective, and multidimensional material catering to both sensing and heating applications. However, it still lacks essential features such as high temperature performance with low power usage, high strength, and robustness of thin films in tough environments such as heating elements in thermal socks. Hence, in this paper, we demonstrated laser induced graphene (LIG) as a suitable candidate for wearable thermal applications. LIG heaters were fabricated using a cost effective and environmentally friendly technique based on photothermal ablation of polyimide substrate using a 50 W CO2 laser. The heat flux of LIG heater was improved by stacking multiple films while their electrical connections are made in parallel. Upon joule heating, the heaters had excellent electrothermal performance, fast and stable response, achieving temperature of 195 °C using a relatively low DC voltage of 10 V. Most importantly, they showed good durability after bending, washing and repeated heating and cooling cycles. Due to these advantages, the LIG-based thin film heaters have potential as reliable and low-cost heating elements for variety of tough applications such as defrosting and wearable thermal pads.

Numerical Investigation of the Two-Phase Closed Thermosyphon Operating with Non-Uniform Heat Flux Profiles

The two-phase closed thermosyphon (TPCT) or wickless heat pipe has been widely considered as an extremely effective and low-cost heat removal device for various applications. A computational fluid dynamics (CFD) investigation of the TPCT can provide detailed information regarding its design and development. In this study, the effect of non-uniform heat-input profiles on a vertical TPCT has been investigated. A CFD model has been built to simulate the evaporation and condensation processes within the TPCT investigated, using a solver based on OpenFOAM which has been modified and validated against experimental data reported in the open literature. Four non-uniform heating profiles of the TPCT have been investigated, and the effects these have on the internal flow field within the pipe are discussed. Simulation results show that the non-uniform heat flux profiles can impact thermal performance depending on the overall heat loading and the heat flux profile.

Low-cost heat exchanger benches for remote operation

The COVID-19 pandemic created significant challenges in operating the lab component of undergraduate courses and promoting active learning, with only a short time available to implement alternative teaching methods. In this work a low-cost platform for distance operation and assessment of replaceable bench-scale heat exchangers was developed to provide students an opportunity to observe the transient and steady-state behavior of heat exchangers while unable to access lab facilities. Each workbench had a new material cost of approximately C$5 000. Operation of physical equipment provided students the opportunity to observe non-ideal behavior and compare various heat transfer correlations which may not be seen in process simulators. The developed platform implemented an Arduino microcontroller for low-cost process control. Equipment was seamlessly slotted in to the existing course upon the return to on-campus learning and provided a more stable system when compared to previously existing lab experiments. Most learning outcomes were observed in remote and in-lab experiments and challenges faced in remote operation are highlighted. No statistically significant difference was observed in student performance between students completing lab experiments remotely and students completing experiments in-lab.

Heat transfer analysis of hollow channel in phase change materials spherical capsule

• A PCM spherical capsule with simple and low-cost hollow channel is presented. • The conduction and natural convection in the center of capsule are enhanced. • The effect of angle and diameter are investigated experimentally and numerically. • The heat storage time reduced by 28% with a dimensionless diameter of 0.25. The packed bed thermal energy storage device (PBTESD) filled with spherical phase change capsules can overcome the mismatch between the energy supply and the heat demand, which has broad application prospects. In this paper, a spherical phase change material capsule with a hollow channel with a simple, low-cost heat transfer enhanced structure has been proposed and studied. Experiments were carried out to measure the temperature of the typical capsule and capsule with hollow channel during the melting process to study the feasibility of the structure. Moreover, a three-dimensional numerical model based on the enthalpy method is established and verified by experiments. In order to optimize the structure and study the effect of random placement on the performance of hollow channels, the effects of the angle and diameter of the hollow channel on the thermal performance are analyzed by numerical simulation. A 24% increase in melting rate is found through experimental temperature profiles preliminarily. Besides, it is found that the performance decreased by 26.7% when the angle of the hollow channel decreasedfrom 30° to 0°, and the performance is similar when the angle is between 30° and 90°. In addition, the energy storage time decreases linearly with the increase of the diameter when the dimensionless diameter d/D is bigger than 0.05. Increasing the dimensionless diameter can improve the performance of the hollow channel, but it also reduces the phase change material filling rate. The melting time is shortened by about 28% when d/D=0.25. This paper indicated the transient thermal properties of the spherical capsule with hollow channel during constraint melting, which laid a foundation for further structural optimization and practical application.

Reverse Thinking: The Logical System Research Method of Urban Thermal Safety Pattern Construction, Evaluation, and Optimization

The acceleration of urbanization has significantly impacted the changing regional thermal environment, leading to a series of ecological and environment-related problems. A scientific evaluation of the urban thermal security pattern (TSPurban) strongly benefits the planning and layout of sustainable development and the construction of comfortable human settlements. To analyze the characteristics of the TSPurban under cross-regional differences and provide targeted solutions to mitigate the urban heat island effect in later stages, the logical system research framework of the TSPurban based on the “construction–evaluation–optimization” model was explored using reverse thinking. This study selected the Wuhan metropolitan area in China as the research object. First, a morphological spatial pattern analysis (MSPA) model was used to extract the top 30 core heat island patches, and Conefor 2.6 software was used for connection analysis to evaluate their importance. Second, based on the characteristics of various land cover types, the friction (cost) map of surface urban heat island (SUHI) diffusion was simulated. The spatial attributes of the heat island resistance surface were examined using a standard deviation ellipse and hot spot analysis. Finally, this paper used circuit theory to find 56 low-cost heat island links (corridors) and circuit scape software to find widely distributed vital nodes. The optimization of the TSPurban network was then investigated using a reverse thinking process. Heat island patches, corridors, and vital nodes are among the crucial components of the TSPurban. By obstructing corridor links and disturbing important nodes, it is possible to appropriately and proficiently reduce the TSPurban network’s connection efficiency and stability, which will have a positive influence on regional climate mitigation and the heat island effect.

Barocaloric Properties of Thermoplastic Elastomers

Solid-state refrigeration represents a promising alternative to vapor compression refrigeration systems which are inefficient, unreliable, and have a high global warming potential. However, several solid-state cooling technologies—including those relying on a temperature change induced by an applied electric field (electrocaloric effect), magnetic field (magnetocaloric effect), and uniaxial stress (elastocaloric effect)—have been investigated, but their efficiency and scalability remain a concern. Materials with a large barocaloric response—temperature/entropy change induced by hydrostatic pressure—hold a significant promise for solid-state cooling but remain comparatively less explored. These materials need to be inexpensive, compressible, and show a large barocaloric response around the temperature of interest. Soft materials have the potential to meet these requirements and enable the development of low-cost high-efficiency solid-state heat pumps. Here, we investigate the barocaloric performance of commercially available block copolymer thermoplastic elastomers. We characterized the mechanical, thermal, and barocaloric properties of these materials and evaluated their potential for solid-state refrigeration. We utilized rheometric measurements to evaluate the isothermal compressibility and normalized refrigerant capacity of the thermoplastic elastomers. In addition, we directly measured the pressure-induced temperature change of the test materials and compared them with their normalized refrigeration capacity. The measured isothermal compressibility was in the 0.1–0.4 GPa−1 range, while the normalized refrigeration capacity varied between 13.2 and 41.9 kJ K−1 GPa−1 for a 100 MPa applied pressure and 65°C temperature span. The corresponding pressure-induced temperature change for an applied pressure of 434.1 MPa varied between 2.2 and 28°C. These results demonstrated the superior barocaloric properties of thermoplastic elastomers and their promise for next generation barocaloric solid-state refrigeration devices.

시추공식 계간축열 시스템을 이용한 4세대 지역난방 공급 및 효율 개선 연구

The purpose of this study was to compare the conventional Geothermal Source Heat Pump (GSHP) System, with Borehole Thermal Energy Storage (BTES) utilized heat pump system in cost-wise criteria. The consecutive operation of conventional GSHP performance decreased annually, and eventually discharged the purpose of the system. Deploying the BTES system with heat pump, thereby accumulating the low-cost heat energy from the summer season and using it to ease the heating load peak, can manage the presented problem, as well as supply the sufficient and stable amount of heat energy. Additionally the estimated heat pump capacity of conventional GSHP was 7,864 kW and BTES utilized system showed 1,781 kW. The land area occupancy also decreased by 25%. The BTES system can successfully decrease the initial facility investment cost and make efficient use of ground space.

Experimental investigation of a novel split type vacuum tube solar air thermal collection-stepped storage system (ST-VTSATC-SSS)

A novel split type vacuum tube (VT) solar air thermal collection-stepped storage system (ST-VTSATC-SSS) is proposed in this study to address the problem of carbon and pollution emissions from coal-fired heating in rural areas. A VT air collector is used to decrease heat loss. Paraffin and lauric acid are used to conduct thermal stepped storage. The performance of ST-VTSATC-SSS is experimentally investigated. On the coldest day in winter in 2021(Ta = −2.1 °C), the collector efficiency is 61.7%, the collection-storage efficiency is 40.7%, and the heat storage is 13.7 MJ. During the thermal collection process, the thermal collection-storage efficiency can be improved by enhancing the air volume flow rate, it decreases with the enhancement of solar radiation, and it can reach 55.3%. During the thermal discharge process, increasing the air volume flow rate can enlarge the discharge power. The average discharge power can reach 904 W. The result reveals that ST-VTSATC-SSS can rapidly release heat. Besides, a heating application for the master bedroom is analyzed. In the heating season, this mechanism can save coal of 373.0 kg and reduce CO2 by 977.3 kg, and the heating cost is 14.6 ¥/GJ. The ST-VTSATC-SSS contributes a new, clean, and low cost heating method in rural building heating.

The Geobattery Concept: A Geothermal Circular Heat Network for the Sustainable Development of Near Surface Low Enthalpy Geothermal Energy to Decarbonise Heating

Decarbonisation of heating represents a major challenge in efforts to reach Net Zero carbon emissions, especially for countries that rely heavily on the combustion of carbon-based fossil fuels to meet heating demand such as the United Kingdom. In this paper we explore the use of near surface low enthalpy geothermal energy accessed via commercial and domestic heat pump technology. These resources may become increasingly important in decarbonisation efforts but, while they are renewable, their sustainability is contingent on appropriate management. Here, we introduce a new geothermal circular heat network concept, known as a “geobattery,” which redistributes recyclable heat from emitters to users via elevated permeability pathways in the subsurface and offers a platform to manage shallow geothermal resources. If successfully implemented the concept has the potential to provide low carbon, resilient, low-cost heating that is sustainable both in terms of heat pump performance and the shallow geothermal resource. We demonstrate the concept based on the cooling requirements of a case study data centre with existing high energy use and the potential to inject the generated heat into elevated permeability pathways in the shallow subsurface. We show that thermal recharge under these conditions has the potential to arrest subsurface temperature declines associated with closely spaced borehole heat exchangers, ensure the long-term sustainability of shallow geothermal resources for generations to come, and play an important role in the decarbonisation of heating.

A comparative study of different low-cost sensible heat storage materials for solar air heating: an experimental approach

ABSTRACT Among various applications of solar energy, solar air heater is a common method to fulfill the demand of hot air for space heating. In this experimental work, a low-cost solution is discussed for solar air heating. This solution deals with integration of modified models of air heaters with graphite powder, brick powder, and desert sand. These sensible heat storage materials have been filled inside a small cylindrical-shaped container to be placed over the absorber of modified heaters for performance enhancement. Total three different configurations have been developed for comparative analysis such as, configuration 1 for graphite powder testing, configuration 2 for brick powder testing, and configuration 3 for desert sand testing. Results are compared to the same design conventional heater to find out the best configuration, which shows that the configuration 1 is the best among all tested configurations. Under the configuration 1, enhanced heat transfer is observed about 541.2 W/m2K, thermal efficiency about 37.62%, overall heat loss about 6.71 W/m2K, and maximum exhaust air temperature about 41.2°C. For a better comparative analysis, configuration 1 is further compared to some other designs of solar heaters purposely for the plate temperature and thermal efficiency. Total cost of the best configuration (model) is about $59.5.