Collector Storage Solar Water Heater Research Articles

An advanced Photovoltaic Thermal Collector Storage Solar Water Heating based on planar liquid vapour thermal diode: Model-based design approach for the optimal energy performance assessment

The building sector is responsible for the highest portion of energy consumption and carbon dioxide emissions. To partly address this issue, the scientific community is placing greater emphasis on the utilization of Building Integrated Solar Systems (BISS) as a means of improving building thermophysics and decreasing primary energy demand. Within this framework, Integrated Collector Storage Solar Water Heaters (ICSSWH) have the potential to significantly decrease the costs associated with the installation and maintenance of building-integrated solar systems (BISS), all while optimizing the utilization of solar power. Nevertheless, ICSSWHs exhibit certain limitations in their capacity to retain thermal energy, particularly during nocturnal periods. One potential approach for enhancing the efficiency of ICSSWH collectors involves the integration of Thermal Diodes (TD), which have the capability to optimize heat absorption while minimizing heat retention. In this context, to advance the state-of-the-art in the field, this paper presents a novel dynamic simulation tool conceived to assess the performance of an innovative Hybrid Photovoltaic Thermal ICSSWH (the HyPVT), incorporating a cutting-edge Planar Liquid Vapour Thermal Diode (PLVTD), and purposely designed to be integrated into buildings’ envelope. By using the developed simulation tool, the performance of the proposed HyPVT collector concept is investigated with the aim of assessing its collection and retention efficiencies under different boundary and operating conditions. Furthermore, to show the effect of the Planar Liquid Vapour Thermal Diode (PLVTD) adoption, a comparative analysis is conducted between the proposed ICSSWH and a conventional one (without a thermal diode). Finally, the developed tool will be utilized in forthcoming research to determine the optimal device configuration through the utilization of a model-based design methodology.

Dynamic testing of a new integrated collector storage solar water heater (ICSSWH) according to standard ISO 9459‐5: Use of a numerical approach for long‐term prediction in different climatic conditions

AbstractThis work analyzes the performance of a new Integrated Collector Storage Solar Water Heater (ICSSWH) by using Dynamic System Testing (DST) method according to Standard ISO 9459‐5. The long‐term performance study of the system in different climatic conditions has been achieved by a coupling model between DST results and a numerical approach based on the system transient behavior. Results of the experimental dynamic system evaluation showed that the total store heat capacity Cs, the useful collector surface Ac* and the storage tank heat losses coefficient Us are, respectively, 0.87 MJ/K, 1.21 m2 and 10 W/K. In Tunisian climatic conditions, the ICSSWH system allows covering until 79.3% from a typical family need for a daily consumption of 170 L. The results found allow optimizing the energy gain of the ICSSWH as well as selecting a specific load volume according to the location. Especially, investigations showed that in Stockholm and Riadh climatic conditions, the ICSSWH's solar fraction reached 27% and 83%, respectively, for a daily load volume of 250 L. More importantly, the experimental effort of DST identification can be minimized by coupling DST data with a robust numerical approach.

Multi-objective optimization for comparative energy and economic analyses of a novel evacuated solar collector prototype (ICSSWH) under different weather conditions

This paper aims at optimizing the energy performance of an innovative integrated collector-storage solar water heater (ICSSWH) prototype. The system incorporates a high-vacuum gap, which significantly reduces convective thermal losses, and a serpentine absorber system coated with a low-E layer to minimize radiative thermal losses.The methodology is based on a detailed dynamic simulation model, implemented in the MatLab environment, suitable conceived to accurately predict the energy performance and economic profitability of the ICSSWH under various weather conditions and energy market prices. This approach aims to initially identify the most influential geometrical, thermophysical and optical parameters that impact the energy performance of the system through the assessment of different objective functions. After identifying the most influential parameters, the range of existence with the interval step for each variable is defined, and the optimization procedure is conducted to determine the optimal set of variables that maximize/minimize the selected objective functions.To demonstrate the effectiveness of the proposed methodology, a proof of concept was conducted to optimize the energy performance of novel ICSSWH by considering nineteen parameters with the aim of maximizing/minimizing three different objective functions. The results of this analysis yielded various sets of optimised parameters for the ICSSWH. Therefore, by implementing the set of optimised parameters into the dynamic simulation model, the energy performance of the optimised and non-optimised ICSSWH collectors was evaluated in 42 different weather zones and compared to a reference case scenario.

Thermal assessment of a new planar thermal diode integrated collector storage solar water heater in different partial vacuums: An experimental study

Thermal diodes are novel mechanisms with high thermal resistance in one direction and low thermal resistance in the other. The current study introduces a new planar thermal diode integrated collector storage (ICSs) system and analyzes its transient dynamics and performance under field conditions in several scenarios, including operating at atmospheric pressure and partial vacuums: Ptotal = 0.7 atm and 0.5 atm. The acquired data illustrate that the collector has approximately the same transient dynamics during the collection period, while differences pronounce during the retention period. Utilizing partial vacuums is tricky and may cause to decrease in performance; however, the best retention and collection efficiencies were obtained at 16.97% and 29.33% when Ptotal = 0.7 atm was utilized. Increasing the partial vacuums to Ptotal = 0.5 atm decreases the retention efficiency significantly to nearly 3.26%. The heat gain (forward mode) coefficient was not affected significantly by partial vacuums. However, the heat loss (reverse mode) coefficient was reduced by nearly 17.63% at Ptotal = 0.7 atm compared to atmospheric pressure. The calculated heat gain and heat loss coefficients are 9.28 W/k and 19.65 W/k at Ptotal = 0.7 atm; hence, the constructed thermal diode successfully serves as a unidirectional heat transfer mechanism.

Experimental evaluation of a solar water heater integrated with a corrugated absorber plate and insulated flat reflectors

<abstract> <p>When it comes to renewable energy, solar water heaters are among the fastest-growing technologies. Comparatively speaking, integrated collector-storage solar water heater systems cost less than other solar water heater designs. Therefore, both the construction and the operation of a combined collector-storage solar water heater are quite straightforward. The integrated storage solar collector coupled with reflectors has been experimentally investigated. The reflectors were insulated from the back side when working during the day hours and as insulated cover during the night hours. While comparing the combined collector-storage solar water heater with and without insulated reflectors, the results showed that the insulated reflectors increased the thermal efficiency by 23%. Furthermore, on the coldest day, the stored water reached a high of 82 degrees Celsius, though it was only 46 degrees Celsius that same morning.</p> </abstract>

Performance analysis and experimental validation of a vee‐corrugated absorber integrated collector storage solar water heater

AbstractThis paper focuses on enhancing the energy collection efficiency of an integrated collector storage solar water heater (ICS SWH) by vee‐corrugating the absorber and optimizing the design for the vee‐included angle through simulation and experimental study. This paper presents an efficient algorithm for analyzing a vee‐corrugated absorber ICS SWH using Engineering Equation Solver Software. For validating this algorithm, two models of ICS SWH systems have been fabricated: one with a flat absorber and the other with a 60° vee‐included angle corrugated absorber with eight corrugations. The basic purpose of the fabrication of the flat absorber ICS SWH system was to approximate the absorptivity of the absorber. A typical value of 0.68 was estimated for the absorptivity of the aluminum absorber coated with nonselective black paint. After the experimental investigation of the 60° vee‐included angle ICS SWH system, it was found that the real‐time readings were in close agreement with the numerical model readings. For comparison with the previous work, a five‐corrugation system with an approximate 90° vee‐included angle with the same projected dimensions was modeled and the efficiencies of both the models for the time from 7 a.m. to 3 p.m. were calculated. The efficiency of the eight‐corrugation model was 42.56%, which was better than the previous work of the five‐corrugation model, with a 38.86% efficiency for the same ambient conditions. Also, it was theoretically deduced that we had an optimized system at 18 corrugations and a vee‐included angle of 28.78°.

Numerical investigation of the effect factors on the performance of a novel PV integrated collector storage solar water heater

Due to the lower cost and compact structure, Photovoltaic Integrated Collector Storage Water heater combined (PV– ICSSWH) is an alternative form of PV/T system that differs from traditional flat-plate or vacuum tube PV/T system. An analysis was carried out to investigate the effect of operating parameters and structural factors on system performance. A numerical model was developed to predict the performance of the systems. To validate the numerical model, a prototype system was built and tested. The influence of solar radiation, ambient temperature, the thickness of systems, and the aspect ratio of systems was analyzed and the results indicate that: (a) The aspect ratio has a negligible effect on the efficiency. However, it has a significant influence on temperature stratification. (b) As the thickness of the system drops from 100 mm to 60 mm, its total efficiency descents from 55.1% to 52.7% and the relationship is given. (c) The total efficiency only decreases from 54.7% to 53.5%, when the solar radiation rises from 400W/m2 to 800W/m2. (d) As the ambient temperature increases from 283K to 303K, the total efficiency of the system ascends from 45.6% to 61.4%. (e) The total efficiency is about 48.0% in Lanzhou, China which is predicted.

Design, Energy, Environmental and Cost Analysis of an Integrated Collector Storage Solar Water Heater Based on Multi-Criteria Methodology

The paper presents a design and operation analysis of an Integrated Collector Storage (ICS) solar water heater, which consists of an asymmetric Compound Parabolic Concentrating (CPC) reflector trough, while the water tank comprises two concentric cylinders. The annulus between these vessels is partially depressurized and contains a small amount of water in the bottom of the outer vessel which dominantly contributes to the heat transfer from the outer to the inner cylinder. A multi-criteria optimization algorithm is applied to re-evaluate the design specifications of the parabolic surface, thus modifying the design of the entire ICS system and predict the necessary number of units for achieving the highest possible effectiveness with minimized fabrication costs and environmental impacts. The environmental footprint of the device is assessed through Life Cycle Assessment (LCA). The produced thermal energy in conjunction with the environmental and economic results are evaluated as a function of different configuration parameters regarding the water storage conditions, the solar radiation and the total pressure inside the annulus. The ultimate aim of the evaluation process is to offer new perspectives on the design principles of environmentally friendly and cost-effective devices with improved thermal performance.

A comprehensive review on integrated collector-storage solar water heaters

Conversion of solar energy to heat energy is a cost effective, sustainable and an efficient technology to heat water. Solar integrated collector-storage type of water heaters (ICSSWH) is a water heating device which alchemizes solar radiation directly into heat so that it is used for water heating. These systems are compact, simple in design and free from copper tubes bounded structures which unnecessarily causes heat losses and leakage issues. Their collection efficiency is usually higher than commonly used flat plate collectors (FPC). Despite of many advantages, the main disadvantage of compact integrated collection-storage type of water heaters (ICSSWH) is high heat losses during night hours which decreases the water affects the thus decreases the overall efficiency of the system. However, there are some strategies to minimize this heat loss from the system at the time when sunshine is not available; some of the methods are discussed in this paper. Moreover, in this article, the authors discuss the latest development in the new and improved compact water heater designs. In present paper authors critically reviewed various designs of ICSSWH. Use of insulated cover during night, introducing baffle plate structure, using PCM materials and using reverse thermosyphon valve are some of the strategies to minimize the heat losses from the system these methods are discussed in the present paper. Connecting tanks in series is also an effective method to overcome this problem of heat loss during night. In this paper the effect of connecting tanks in series on water temperature has been discussed. This paper presents an overall summary on compact ICSSWH systems which can be useful for further research to design and develop a new small size solar water heater.

A prototypal high-vacuum integrated collector storage solar water heater: Experimentation, design, and optimization through a new in-house 3D dynamic simulation model

Integrated collector storage units are typically affected by convective and radiative heat losses which significantly reduce their energy performance. To enhance solar collection and heat retention, innovative techniques and novel design of such units are being more and more developed. In this framework, this paper focuses on the design and optimization of a prototypal high-vacuum integrated collector storage solar water heater. The proposed unit allows for reaching high temperatures of the stored water and for reducing the temperature drop during non-collection periods. This goal is achieved by suppressing the convective heat losses into the system by keeping the pressure into the related enclosure below 0.01 Pa and by applying a special selective coating to the solar absorber surface to drastically reduce radiative losses as well.In this paper, details about the system design and the conducted experimental tests are reported. In addition, a new mathematical model able to assess the energy performance of the innovative prototype is presented. This tool, based on a detailed 3-D transient finite-difference thermal network, was validated against the gathered experimental data. By such a tool the optical properties of the adopted selective coating are optimized for maximizing the system thermal efficiency. Finally, with the twofold aim of showing the potentiality of the developed code, as well as the effectiveness of the presented innovative solar collector prototype, a comprehensive case study referred to three different European weather zone is presented. Promising results in terms of energy savings (0.73 MWh/y) and CO2 emission reduction (149 kgCO2/y) are achieved.

Effect of Phase Change Materials Integration on the Thermal Performance of a Parabolic Trough Collector

AbstractIn this paper, a parabolic trough collector (PTC) is studied, and its thermal performance is compared to that of an integrated collector storage solar water heater (ICSSWH). The effect of t...

Optimization of phase change thermal storage units/devices with multichannel flat tubes: A theoretical study

Collector storage solar water heater systems that use phase change materials as heat storage media have attracted increasing attention because of their clean, pollution-free properties and high energy storage density. The design and application of these systems require efficient and optimized phase change thermal storage units (TSUs). This study aims to optimize a TSU by using theoretical analysis methods and to fill the research gaps attributed to the lack of theoretical analysis. The TSU in this work comprises a multichannel flat tube and rectangular fins as heat exchange elements. The performance levels of this TSU, including its effectiveness, compactness factor, gravimetric specific power, and fin efficiency, under different structures are compared. The economic viability and energy efficiency of the proposed solar collector phase change thermal storage system are preliminarily evaluated. Results indicate that the structure of the multichannel flat tube TSU is relatively reasonable when the fin aspect ratio (Hfins/x) and thickness are 8.60 and 0.001 m, respectively. The effectiveness of the optimized TSU during charge and discharge processes respectively increases by 52.0% and 16.3% relative to the original multichannel flat tube TSU. The corresponding recommendation for the use of multichannel flat tube TSUs in household baths is four groups/person.

BIPV/T facades – A new opportunity for integrated collector-storage solar water heaters? Part 1: State-of-the-art, theory and potential

Building Integrated Photovoltaic Thermal (BIPV/T) systems are promising solutions for serving local electricity and heat demands in Net Zero Energy Buildings (NZEB). Despite BIPV/T offering clear energetic and space saving advantages compared to separate BIPV and solar thermal, overheating occurs when no thermal demand exists, resulting in reduced yields, stagnation damage, and excessive fluid pressures. Whilst continuous fluid flows mitigate overheating, corresponding parasitic demands and space requirements are significant (pumps, large storage tanks or heat rejection equipment). This two-part study examines an alternative approach to BIPV/T, addressing overheating by combining BIPV and Integrated Collector-Storage Solar Water Heater (ICSSWH) concepts. Solar heating capabilities of ICSSWH collectors are well established and their overnight heat loss characteristics provide passive overheating control. BIPV-ICSSWH approaches have yet to be investigated extensively. This paper (Part 1 of 2) reviews state-of-the-art and performance benchmarks in BIPV/T and ICSSWH; proposes new performance metrics enabling fairer comparisons; and develops a heat transfer model for BIPV-ICSSWH façade elements employing Planar Liquid-Vapour Thermal Diodes (PLVTD) to regulate absorber temperatures and heat losses. Multi-day solar thermal collection, photovoltaic generation, and overnight heat retention behaviours are simulated in different climates. The modelling results (experimentally validated in Part 2 of 2) suggests BIPV-PLVTD-ICSSWHs with single transparent covers and ς ≈ 90% PLVTD diodicity achieve ηT,col ≈ 60% solar thermal efficiency at N ≈ 0.035m2K·W−1, PV/T performance ratio PRT3 ≈ 75%, and heat loss coefficient Ur,sysAsys/u ≈ 20 W·m−3K−1. The novel BIPV-PLVTD-ICSSWH approach can reduce maximum stagnation by 20 °C compared to conventional BIPV/T and therefore support NZEB realisation during global efforts to tackle the climate crisis.

Thermal performance evaluation and enhancement of a parabolic trough collector

In this article, the effect of concentration technology on the thermal performance of a solar water heating system is investigated. A three-dimensional numerical simulation of a parabolic trough collector (PTC) is carried out using the commercial software ANSYS. The performance of a line-focus concentration system is compared to that of an integrated collector storage solar water heater. The PTC provides more useful heat but has higher nighttime thermal losses. It is proposed to reduce nighttime energy loss by insulating the PTC storage tank. The effects of the insulation coverage strategy and medium are discussed. Numerical results show that the thermal insulation material significantly influences heat transfer. Indeed, addition of glass wool reduces heat collection during the day and improves heat preservation at night, while adding an air-filled glass tube increases heat transfer during the day and reduces nighttime thermal losses. The effect of tank insulation coverage is also investigated. This solar system performs best when the upper half of the tank is insulated. The maximum water temperature is 360.5 K, the overall thermal loss coefficient is 9.38 W/m2 K, and the nighttime thermal loss coefficient is 6.2 W/m K. The optimum PTC configuration is one in which the upper half of the tank is insulated by a 0.01 m-thick layer of air that is held in place by glass. This optimized system provides 29% more useful heat, a lower overall heat loss coefficient of 14.9%, and a lower nighttime heat loss coefficient of 62% than the non-insulated-tank-based PTC.

Vertical Planar Liquid-Vapour Thermal Diodes (PLVTD) and their application in building façade energy systems

Buildings represent one-third of global energy consumption and corresponding CO2 emissions which can be reduced through enhanced insulation and building integrated renewables. Thermal diodes can potentially revolutionise passive heat collection/rejection devices such as Integrated Collector-Storage Solar Water Heaters (ICSSWH) and Climate-Control Building Envelopes (CCBE) employed for decarbonisation. We present novel theoretical and experimental validation work on a lumped parameter heat transfer model of Planar Liquid-Vapour Thermal Diodes (PLVTD) to support development of ICSSWH and CCBE components for building facades. This study augments our previous work on a passive horizontal PLVTD model, by introducing falling film evaporation, vapour convection in vertical rectangular enclosures, condensation on vertical plates, and a methodology for evaluating working fluid temperatures. Experimental validations are presented for vertical aluminium (Ap = 0.15 m2, x = 22 mm) and stainless steel (Ap = 0.98 m2, x = 70 mm) prototypes using two different laboratory test methodologies where temperature setpoints were controlled and measured. The model predicts measured steady state thermal conductances in reverse mode (Ur ≈ 12 W·m–2 K−1 and Ur ≈ 1.7 W·m–2 K−1 for x = 22 mm and x = 70 mm PLVTDs respectively) and forward mode (175 < Uf < 730 W m–2 K−1 and 50 < ULvL < 900 W·m–2·K−1 respectively) with reasonable accuracy across investigated ranges (15 < T2 < 65 °C condenser temperatures, 5 < –ΔT12 < 25 °C reverse mode plate-to-plate temperature differences, 50 < q/A < 1000 W·m−2 forward mode heat fluxes). Forward mode behaviour is determined by working fluid vapour mass flow driven by heat flux and influenced by temperature dependent vapour viscosity. Reverse mode behaviour is determined by vapour convection, plate-to-plate radiation, and envelope/structure conduction. Parametric design influences are theoretically examined and ς > 99% diodicity relevant to CCBE and ICSSWH applications is demonstrated experimentally. Study findings contribute towards global efforts tackling the climate crisis by enabling commercial R&D for new Net Zero Energy Building components.

BIPV/T facades – A new opportunity for integrated collector-storage solar water heaters? Part 2: Physical realisation and laboratory testing

Building Integrated Photovoltaic Thermal (BIPV/T) systems which generate electricity and heat simultaneously are promising solutions for Net Zero Energy Buildings (NZEB). Despite BIPV/T offering clear energetic and space saving advantages compared to separate PV and solar thermal, overheating problems occur when no thermal demand exists, resulting in reduced yields, stagnation damage, and excessive fluid flow pressures. This two-part study examines an alternative approach combining BIPV, Planar Liquid-Vapour Thermal Diodes (PLVTD) and Integrated Collector-Storage Solar Water Heaters (ICSSWH) to achieve BIPV/T functionality and retain heat overnight to minimises parasitic demands and reduce overheating. The introductory paper (Part 1 of 2) established novelty and rationale for BIPV-PLVTD-ICSSWH concepts, reviewed state-of-the-art and performance benchmarks, and used theoretical modelling to predict behaviour from key design and operational parameters. This paper (Part 2 of 2) describes prototype realisation and multi-day solar simulator laboratory thermal and photovoltaic testing for covered and uncovered variants exposed to different irradiance levels. Measured solar thermal efficiencies with and without transparent covers were ηT,col = 60% and 58% respectively under zero heat loss conditions whilst overnight heat loss coefficients were Ur,sysAsys/u = 23.0 and 25.4 W·m–3 K−1 respectively, showing good agreement with theoretical predictions. Photovoltaic performance reduced with increasing absorber temperature as expected, although maximum power point efficiencies (ηE,mpp = 11.4% at T1 ≈ 25 °C and 5.6% at T1 ≈ 89 °C, without cover) were lower than expected owing to partial delamination and PV cell damage. The work demonstrates practical operation of a vertical BIPV-PLVTD-ICSSWH, identifies key areas for design development, and highlights benefits of application in NZEB facades.

Experimental characterisation of different hermetically sealed horizontal, cylindrical double vessel Integrated Collector Storage Solar Water Heating (ICSSWH) prototypes

Existing Integrated Collector Storage Solar Water Heaters (ICSSWHs) are typically simple and low-cost devices that combine heat collection and storage functions in one unified vessel. However, during non-collection periods they are affected by higher heat loss characteristics when compared to standard solar collector systems. This paper introduces the design evolution of new horizontal cylindrical ICSSWH prototypes developed at Ulster University that use novel, patented double vessel, thermal diode features (to enhance heat retention during non-collection periods) achieved by incorporating a liquid–vapour phase change material (PCM) with a very low pressure annular cavity. The energy performance evaluation and characterisation of different prototype designs under solar simulated experimental conditions has been conducted and the subsequent parametric analysis presented. A balance between performance and physical/operational considerations is necessary to ensure that new and practical design solutions (in materials, fabrication and assembly) can be formulated to improve the performance of the ICSSWHs within the limits of commercial reality. The importance of augmenting heat transfer across the annulus cavity has been demonstrated with improvement of the cold-start daily collection efficiency from around (ηcol) of 20% (no HTF), to > 55% when the annulus is evacuated to remove non-condensable gases and form a liquid–vapour phase change thermal diode. Annulus thermal diode heat transfer coefficients of around (Ufr) 35 W/m2K in forward mode and 2 W/m2K in reverse mode have been demonstrated. Diurnal thermal efficiencies (ηcol24) of 22% have been measured, but values of 39% have been identified as achievable in the longer-term development of presented ICSSWH.

Modelling and experimental evaluation of an innovative Integrated Collector Storage Solar Water Heating (ICSSWH) prototype

An advanced mathematical model capable of simulating the energy performance of an innovative Integrated Collector Storage Solar Water Heater (ICSSWHs) is presented. Usually, ICSSWH devices available in the market are typically simple and low-cost, combining solar heat collection and storage functions in one unified vessel. However, they exhibit higher heat loss characteristics when compared to standard solar collector systems, with a subsequent reduction in energy performance during night-time and non-collecting hours. An innovative ICSSWH prototype was developed at the Centre for Sustainable Technologies (CST) at Ulster University using a patented, innovative thermal diode feature, attained by incorporating a liquid-vapour phase change material (PCM) and very low pressures. In order to fully investigate the energy performance of the proposed prototype, a suitably dynamic simulation model has been developed and validated in MatLab environment. All modelled temperatures are ±1 °C from the respective experimental measurements. The developed model has been used to evaluate the ICSSWH energy performance by varying several pivotal parameters (physical features and materials) in order to produce an optimised device.

Simulation and experimental validation of solar radiation distribution on the absorber of a line-axis asymmetric compound parabolic concentrator

This paper reports the development and application of a new practical photovoltaic (PV) cells based device to measure the solar radiation flux produced by non-imaging Compound Parabolic Concentrators (CPCs) on cylindrical absorbers. The flexible experimental device comprises 12 discrete miniature PV panels that measure solar radiation on the surface of a cylindrical absorber. The device has been used to evaluate the performance of an asymmetric CPC system and results validated with a computer-based Ray Tracing Model. The study attained significant agreement between outdoor results of the experimental device and results of the ray tracing simulation with a difference of <9% in optical efficiencies. The non-imaging reflector illuminates a targeted section of the absorber of a horizontal east-west thermal diode Integrated Collector Storage Solar Water Heater. During outdoor testing, the experiments indicated a local concentration ratio reaching 1.4 suns on the targeted section of the absorber vessel surface for incidence angles -30°≤θi≤30°, confirming technical suitability of the asymmetric CPC for deployment in locations at equatorial latitudes.

Analysis of the thermal efficiency of a compound parabolic Integrated Collector Storage solar water heater in Kerman, Iran

This paper presents an experimental study involving the design, manufacturing and testing of a prototype integrated collector storage (ICS) solar water heater (SWH) in combination with a compound parabolic concentrator (CPC). The thermal efficiency of the developed system is evaluated in Kerman (latitude 30.2907° N, longitude 57.0679° E), Iran. The developed system is intended to supply hot water for a family in remote rural areas. A 6-month experimental study was undertaken to investigate the performance of the ICS SWH system. The mean daily efficiency and overnight thermal loss coefficient of each experiment were analyzed to examine the appropriateness of these collectors for regions in Kerman. The results showed that mirror has the highest mean daily efficiency (66.7%), followed by steel sheet (47.6%) and aluminum foil (43.7%). The analysis of hourly and monthly operation diagrams for variations of water temperature for the developed ICS system showed that by increasing the amount of radiation entering the water heater, the thermal efficiency of the system decreases, such that the highest efficiency was in April and the lowest in July. With the distribution of radiation intensity in the months of August and September, the thermal efficiency of the system increased. This regional study illustrates how selecting a proper concentrator can increase the thermal efficiency of this solar-based system. It also shows how the temperature gradient between the ambient air and internal water in the storage tank can influence the performance of such systems, and how a controlled amount of hot water withdrawal can affect the system’s efficiency. Developing the ICSSWH system is an ideal sustainable solution in countries that benefit from a large amount of solar intensity.