Solar Water Collector Research Articles

دراسة عملية لاداء سخان ماء شمسي ذو الدوران الطبيعي المتصل على التوالي

This research paper presents an experimental study on the performance of a natural circulation solar water heater system with two typical collectors connected in series. The paper provides a comprehensive analysis of the system's thermal performance under different load conditions, including no-load, intermittent, and continuous load. Mean storage tank, solar collector means plate (the left) temperature and thermosyphon flow rate in a vertical tank were measured. Results showed that there was variation in solar water tank and collector plate temperature under load and no-load conditions. Analysis of thermal performance of the system was conducted for each condition. The highest plate temperature (100 ˚C or even more) with no circulation of both collector and load conditions, indicate the high quality of the solar collectors even during the cold season. The collector’s arrangement in series connection is of highest gain in energy and higher storage tank mean water temperature. Several characteristic equations obtained to represent the performance of the present natural circulation system under collector connection arrangement in series. In fact, when large amount of hot water was required for a certain purpose (Industrial sector for example - MSF plant or central heating), multiple collectors are to be deployed in series and in parallel to produce the required amount (quantity) and desired temperature (quality) at the same time. Key words: Thermosyphon solar water heater, storage tank profile temperature, Solar Water Heaters (SWHs), instantaneous efficiency, collector flow factor, collector efficiency factor, collector heat removal factor

Performance improvement of a heat pipe evacuated solar water collector using quartz/water nanofluid: A numerical and experimental study

Solar water collectors (SWCs) are the major element of any solar power system. Evacuated tube solar water collectors (ESWCs) contain multiple evacuated tubes formed between the tubular absorber and the glass cover in each tube to reduce heat losses. In this survey, it is aimed to improve the thermal performance of a heat pipe evacuated tube water solar collectors (HP-ESWCs) by using quartz nanofluid as the working fluid and experimentally and numerically obtained results are explained in detail. The numerical simulation of the heat pipe part of the system aims to present a general view of energy gain by the heat pipe, evaporation of the working liquid inside the pipe and condensation of the vapor by releasing its energy in the condenser section. Also, the performance of the whole collector was experimentally examined utilizing four different working fluids. The outcomes indicate that the thermal efficiency of the HP-EWSC using deionized water varied between 29.63 and 55.78 %, 36.50–61.13 %, 40.73–64.35 % and 32.81–75.92 % at 0.008, 0.016, 0.033 and 0.050 kg/s flow rates, respectively. Also, the efficiency of HP-EWSC using quartz/water changed between the ranges of 43.87–71.95 %, 50.86–78.22 %, 46.37–79.66 % and 55.60–85.64 % at 0.008, 0.016, 0.033 and 0.050 kg/s flow rates, respectively. Average exergy efficiency enhancement by utilizing quartz/water nanofluid in the present work varied in the range of 34.23–99.97 %. General findings of this study clearly showed the positive impacts of using quartz/water as working fluid in the HP-ESWCs on the overall performance.

3E analysis of enhancing solar distillation performance through innovative wick convex stepped absorber, PCM, and evacuated tube solar water collector: Experimental investigation

Solar distillers have been developed to meet daily potable needs because they are simple to construct and easy to operate, especially in arid areas. Despite all this development, their efficiency and yield represent a challenge. Thus, the present study aims to improve the thermo-economic performance of stepped solar distillers via raising the rates of evaporation. This was achieved by shaping the absorber surface into the shape of a convex stepped absorber and incorporating it with the evacuated tube solar water collector as a first case, where different operating times were tested. After that, wick materials were added above the convex stepped absorber. Finally, in the third case, the reservoir of paraffin wax was added below the absorber as a latent storage medium. In all experiments, the performance indicators of the three cases are compared to those of classical solar distiller. As a result, incorporating all the proposed additives (third case) improved the productivity, thermal, and exergy efficiencies by 186.96 %, 44.52 %, and 171.15 %, respectively. In addition, all proposed additions reduced the cost of potable water per L by 16 %. The findings of this investigation demonstrated the sustainability, suitability, and economic viability of the suggested enhancements in the domain of solar distillation.

Thermal Assessment of Evacuated and Flat Plate Collector Solar Water Heater for the Enhancement of Collector Area

Thermal Assessment of Evacuated and Flat Plate Collector Solar Water Heater for the Enhancement of Collector Area

Thermal performance of two evacuated tube solar collectors with flat heat pipes

To promote the transition to clean heating methods in rural areas and improve solar energy utilization efficiency, two new types of solar water collectors with evacuated tubes, namely finned and finless collectors, are constructed with multi-channel flat tubes and flat micro-heat pipe arrays, and comparison experiments are conducted. By integrating with multi-channel flat tubes, the micro-heat pipe arrays, which function as the central heat transfer component, are capable of attaining effective thermal transmission. The multi-channel flat tubes have a substantial surface area available for heat transfer with the thermal fluid, while the evacuated tubes exhibit superior thermal insulation performance. The structural discrepancy between the two collectors lies in the presence or absence of louvered fins attached to the flat heat pipes inside the evacuated tubes. The comparative analysis of the two collectors includes time constant, thermal resistance analysis, distribution of temperature, normalized temperature difference, pressure drop, and actual operation effect under different conditions. The average thermal efficiency of the finless collector (59.4 %) is lower than that of the finned collector (78.2 %) on a typical experimental day. Then, further investigations are conducted to explore the effects of heat transfer fluid volume flow rate and inlet temperature on the thermal performance of finned solar water collector. With the heat transfer fluid volume flow rate of 120 L/h and the inlet temperature at 15 °C, the finned collector can achieve its maximum thermal efficiency of 86.4 %.

INVESTIGATING THE IMPACT OF USING MAGNETIC-TYPE NANOFLUID ON THE THERMAL PERFORMANCE OF A SOLAR WATER COLLECTOR WITH HELICALLY COILED TUBE ABSORBER

In recent years, solar water collectors are commonly preferred for supplying heated water to be utilized in various processes. In the present study, a solar water collector equipped with a helically coiled absorbing surface has been manufactured and experimented under various working conditions to determine its general behavior. The main goal of using a helically coiled absorber is enhancing energy harvest in the collector by ensuring vertical angle between the absorbing area and incident radiation. In addition, for providing greater increase in thermal efficiency, magnetic type nanofluid has been used as a working fluid. In this context, NiFe<sub>2</sub>O<sub>4</sub> nano-sized particles have been mixed with water at the ratio of 2% (wt./wt.). Accordingly, the performance of the collector has been empirically examined using both water and magnetic nanofluid at two different flow rates. The overall results of the present survey exhibited successful use of magnetic type nanofluid in a solar collector equipped with a helically coiled absorbing surface. Utilizing magnetic nanofluid in the collector as circulating fluid raised the thermal efficiency on an average of 20.29% and 23.59% at volumetric flow rates of 0.5 lpm, and 0.9 lpm, respectively. Moreover, utilizing NiFe<sub>2</sub>O<sub>4</sub>/water nanofluid in the water collector enhanced the exergy efficiency on an average of 44.53% and 40.04% at volumetric flow rates of 0.5 lpm and 0.9 lpm, respectively.

Electrical energy saving analysis based on solar power collector’s thermal system

This article analyzed the processes of new types of solar collector water heating systems designed to form solar collector thermal energy, air movement mode, including boundary layers of air flow, based on solar energy due to the abundance of sunny days in Uzbekistan. Additional parts in the interior, pipes, structures of the heating surface, methods for calculating basic physics were indicated. Also, the issues of forming the boundary layers of air flow, determining the elongation of the boundary layers and forming the air movement of the air flow, which occur under conditions of laminar or turbulent flow, are determined by changes in the patterns of air flow movement. A mathematical and immersion model was developed based on the results obtained directly in Reynolds number (Re) in the range 1000-5000 of these thermal and hydrodynamic processes. In the research work, the concave dimensions of the air pipe, including the length of the concave step, were determined taking into account the relationship between t and the concave height h, the formation of air flow movements and the breakpoints of the boundary points. Based on this system, traditional fuel resources were saved as well as energy saving problems in the electric power system.

Investigation of annual thermal performance and techno-economical analyses of direct absorption solar collector by using nanofluids

In this study, the annual thermal performance and techno-economic analyses of a direct absorption solar collector (DASC) using nanofluids were investigated. According to the results of numerical analysis the difference between the specific heat gains was 126.5 W/m2, where difference for annual energy saving or enhancement for solar energy converting to useful was 224 kW/m2a. To sum up utilization of MWCNTs (0.05%) based nanofluids as heat transfer fluids in PTC supported the 13,5% of thermal efficiency in comparison of water. Furthermore, when nanofluids are used as a heat carrier in a solar collector, the cost of 1 kWh of thermal energy is 0.029 $/kWh, and when water is used, it is 0.034 $/kWh. The payback period of the initial investment amount of the nanofluid solar collector is 3.96 years, where the interest rate of the bank is calculated at 23%, and the payback period of the initial investment amount of the water solar collector is 3.99 years.

Investigations on a solar humidification dehumidification desalination system equipped with various packing materials and multi-stage bubble column dehumidifier.

This work presents the theoretical and experimental investigation of a solar-powered humidification dehumidification desalination (HDD) system with different humidifier packing materials and a two-stage bubble column dehumidifier (BCD). Naturally available coconut shells (CS) and coconut shells with drilled holes (CSH) on the surface to improve water permeability were used as packing materials in the humidifier, and their performance was compared with that of commercial-type pall ring (PR) and raschig ring (RR) packings. An in-house developed numerical model of the HDD system in conjunction with a flat plate solar water collector was used in this study. Steady-state experimental results showed that CSH packing exhibited the highest volumetric mass transfer coefficient (0.00852kg/s), resulting in maximum humidifier efficiency (96%) and freshwater yield (2.16kg/hr), followed by PR (0.00841kg/s, 94%, and 2.137kg/hr), CS (0.00831kg/s, 90%, and 2.127kg/hr), and RR (0.0081kg/s, 81%, and 2.087kg/hr) at feedwater mass flow rate of 1.5kg/min and humidifier inlet temperature of 75 [Formula: see text]. Furthermore, transient outdoor test results showed that using a two-stage configuration in a BCD increased the daily average effectiveness to 0.93, as against 0.79 for a single-stage BCD. Employing CSH instead of PR and RR packings in the humidifier reduced freshwater costs by 6.2% and 7.6%, respectively.

Thermal and entropy behavior of sustainable solar energy in water solar collectors due to non-Newtonian power-law hybrid nanofluids

Introduction: Nanofluids, hybrid nanofluid possesses thermophysical features that boost the fluid performance. This research work is motivated by the utilization of water solar collectors that incorporate non-Newtonian, power-law hybrid nanofluid in a three-dimensional model, considering the two-phase model.Method: The primary objective of this study is to transform the governing equations of the flow model into a set of ordinary differential equations by employing the three-parameters group technique. Based on the innovative discoveries, two models incorporating new associated functions have been successfully developed for two distinct scenarios characterized by the power-law index, n. The impact of physical factors on the velocity profile, temperature distribution, concentration field, and entropy output of the system is clearly illustrated through a variety of graphs.Results: The results indicated that the inclination angle of 20° had the best thermal characteristics compared to other inclinations. The entropy generation reached its maximum value at temperature difference of 13 K due to irreversibility of the system, which indicates that the system is more efficient.Discussion: Furthermore, the increasing percentage in Nusselt number is predicted to be 28.18% when the Prandtl number is taken a range. The Sherwood number enhanced up to 18.61% with a range of Brownian motion. A quantitative comparison is conducted between the present results and the literature in order to validate the superior efficiency of the used method.

The thermal impact of stored water as supplementary energy source for a solar air heater

AbstractSolar energy system optimization is a critical consideration for expanding its reach and competitiveness against traditional energy sources. This study specifically targets solar flat plate collectors, focusing on the concept of solar air collectors with an innovative enhancement strategy. To fulfill energy requirements across various applications like heating and drying, setting up collector arrays, such as solar air and water heaters, becomes imperative for meeting desired energy outputs. This research employs numerical analysis to investigate the energy efficiency of a modified solar air heater (MSAH). The enhancement involves integrating a parallelepiped enclosure filled with water, connected to a solar flat plate water collector, into the collector's rear. This water‐filled enclosure serves as a storage tank for the solar water heater. Simulation using the Fluent CFD code is conducted based on meteorological conditions at the Renewable Energy Development Center (CDER) in Bouzaréah, Algeria. Numerical outcomes are compared with experimental findings. Results indicate the positive impact of utilizing the water storage tank as an additional energy source. This modification leads to a substantial 57% performance increase in the MSAH compared with the standard version. This elevated efficiency remains consistent even during periods of reduced solar radiation, owing to the supplementary energy contribution from the solar water heater. In contrast, the standard version's performance hinges solely on available solar radiation for energy generation. This research underscores the potential of combining solar air and water heaters to enhance solar energy systems' efficiency and dependability, facilitating their practical implementation and sustainable utilization.

Thermal performance of a novel water blind-Trombe wall system: A comparative experimental investigation

A traditional Trombe wall suffers from undesired heat gains, single service function, and poor aesthetic appearance, and these drawbacks act as a barrier to its widespread application. This study introduced a newly designed Trombe wall, which neatly incorporated a water-flowing channel and venetian blind (named WBTW). The WBTW can efficiently provide space heating, domestic hot water, and simultaneously act as a shade for reducing cooling load in hot summer. To examine the operating performance of the WBTW under different modes, long-term comparative experiments between a room with the WBTW and that with a flat plate solar water collector (SCCW) and one with a conventional south wall were conducted under realistic climate conditions. Through the test under hot water mode, it was observed that the average thermal efficiency of the WBTW reached 52.8% throughout different seasons, which was 8.2% higher than that of the SCCW. Furthermore, in summer the combined use of external circulation ventilation and water circulation for the WBTW was suggested to avoid overheating phenomenon although that was at the sacrifice of hot water temperature. Space heating experiments showed that the coefficient of thermal comfort enhancement was 0.744 for the room with WBTW under linked air–water heating mode, while that was only 0.155 under stand-alone air heating mode. Finally, based on the validated theoretical model of the WBTW system, a sensitivity analysis of operating and structural parameters was conducted. As to the influence on the annual heat gains of the WBTW system, the order was blinds angle (a) > the ratio of blind spacing to width (r) > air inlet velocity (v) > water mass flow rate (w) > air channel depth (d). The optimum level combination was a = 30°, r = 1, v = 0.4 m/s, w = 0.08 kg/s and d = 0.3 m.

Improving the performance of a heat pipe evacuated solar water collector using a magnetic NiFe2O4/water nanofluid

In the recent years, heat pipe evacuated tube solar collectors (HP-ETSCs) are widely utilized due to their easy maintenance and high efficiency. However, increasing the performance of available systems is an important issue that investigated in many studies. The main goal of this study is improving the thermal performance of a HP-ETSC by replacing the working fluid of the system with magnetic nanofluid. In this context, magnetic type NiFe2O4/water nanofluid has been utilized as working fluid in a HP-ETSC to improve the overall performance of the system. Accordingly, NiFe2O4 nanoparticles has been mixed with distilled water at the ratio of 2 wt% in order to obtain magnetic nanofluid. The performance tests have been performed at various water flow rates (0.016 kg/s, 0.033 kg/s, and 0.050 kg/s) using distilled water and NiFe2O4/water magnetic nanofluid. The general outcomes of this work indicated positive results of using NiFe2O4/water magnetic nanofluid on the efficiency of the HP-ETSC. Utilizing NiFe2O4/water nanofluid in the HP-ETSC as working fluid averagely increased the thermal performance as 37.72%, 39.59% and 44.96% at flow rates of 0.016 kg/s, 0.033 kg/s and 0.050 kg/s, respectively. In addition, using NiFe2O4/water magnetic nanofluid in the HP-ETSC averagely increased the exergy efficiency as 60.59%, 55.61%, 59.61% at flow rates of 0.016, 0.033 and 0.050 kg/s, respectively.

Influence of power-law index and hybrid-nanoparticles concentrations on the behavior of non-Newtonian hybrid nanofluid inside water solar collector

Nowadays, there is great attention given to solar collectors (SCs) for their important applications based on the advantages of nanotechnology and solar radiation. Hybrid nanofluid (HNF) is our first option due to its thermophysical properties that help in improving the overall performance, unlike other nanofluids. This paper gives a detailed novel analysis of SCs with the existence of Newtonian, power-law HNF in unsteady conditions and a three-dimensional model under the consideration of Brownian motion and thermophoresis parameter. In this research, the group transformation method (GTM) and similarity transformation steady state fluid dynamics are used to transform the mathematical model into a simpler system. This coupled system of ordinary differential equations with the related functions, dimensionless entropy generation and Bejan number is achieved at two cases of power-law index. The impact of involved parameters on velocity profile, temperature distribution, concentration field, entropy output of the system and Bejan number is depicted prominently by various graphs. The fluid velocity shows improvement with higher values of power-law index and shape factor, while it diminishes with magnetic parameter and Prandtl number. Enhancing the values of magnetic field and shape factor, results in increase of temperature characteristic which decreases with Prandtl number and power-law index. Increment in the concentration ratio parameter leads to maximize the entropy generation, whereas entropy generation diminishes with higher values of temperature ratio and magnetic parameter. The obtained results and the previously published work are compared qualitatively and quantitatively to each other to validate that the applied method is more efficient. It is predicted that the Nusselt number improves by 28.18% when the Prandtl number is taken range [Formula: see text]. The percentage of increasing in Sherwood number is noted to be 18.61% for range [Formula: see text] of Brownian motion parameter.

Modeling and Experimental Study of a Water Solar Collector Coupled to Optimized Solar Water Still

This work presented the modeling and the experimental study of a water solar collector coupled with an optimized solar still developed in order to boost fresh water produced in a solar distillation system. The desalination process is currently operated under the climatological conditions of Sfax, Tunisia. To numerically simulate the water solar collector, we developed a dynamic model based on heat and mass transfer from the water solar collector. The obtained set of ordinary differential equations was converted to a set of algebraic system of equations by the functional approximation method of orthogonal collocation. The aim of this study was to present the mathematical model and experimental study of this water solar collector

Experimental assessment of novel designed solar hot water storage collector incorporating an array of partitioned ducts absorber

A Novel design of a solar water collector consisting of an array of adjacent partitioned ducts representing the collector absorber is investigated experimentally. Each duct is divided into two flow passages by a partitioned plate made from insulation material. The heated water flows over the partitioned plate to the storage tank, while the cold water flows from the storage tank to the duct down the portioned plate. The designed partitioned ducts solar collector (PDSC) performance is compared to conventional flat plate solar water collectors (FPSC) with the same dimensions and materials. The study is performed under hot weather conditions of upper Egypt for collectors’ tilt angles of; 17°, 27°, and 37°. The findings reveal that PDSC has higher storage water temperature, energy storage, energy efficiency, and lower energy losses. The PDSC has average daily efficiencies of 57.5%, 55.2%, and 47.5%, with enhancement percentages of 31.2%, 32.4%, and 38.6%, relative to the FPSC, at the studied tilt angles, respectively. The PDSC has average exergy efficiencies of 4.47%, 3.71%, and 2.89%, with enhancement percentages of 36.3%, 36.5%, and 41% relative to the FPSC, at the studied tilt angles, respectively. The maximum required thermosyphon heads of the PDSC are 0.8, 0.7, and 0.1, and the corresponding values of the FPSC are 1.7, 1.65, and 0.9 mm at the studied tilt angles, respectively.

Development of sensible heat storage based solar hybrid dryer with evacuated tube collector and biomass gasifier for shrimp drying

The work was aimed at developing an energy-efficient solar hybrid dryer with a biomass-based gasifier heat backup suitable for drying shrimps even during off-sunshine hours. In this dryer, water was utilized as a sensible heat storage (SHS) material as well as heat transfer fluid and biomass gasifier as an indirect backup heat source. The performance of the solar-gasifier hybrid dryer was assessed by drying shrimp (Metapenaeus dobsoni) samples and compared it with solar, and gasifier modes. Shrimp obtained the desired moisture content of 15.09 %, 13.46%, and 14.77% (w.b.) in 9 h, 6 h, and 6 h of drying in solar mode, gasifier mode, and solar-gasifier hybrid drying mode, respectively. The average drying rate of the solar, gasifier and hybrid modes of drying were 0.33 g/g dm.h, 0.46 g/g dm.h, and 0.47 g/g dm.h, respectively. Results revealed that the evacuated tube solar water collector harnessed 193104 kJ and 160185 kJ of heat energy during sunshine hours under the solar and hybrid mode of operation. The maximum drying efficiency of 34.97%, 35.62%, and 41.66% was obtained for gasifier mode, solar mode, and hybrid mode of shrimp drying. The economic evaluation revealed that the hybrid mode of operation is highly economical with the annual savings of $10983.06 and the lowest payback period of 0.62 years.

Thermal Performance Characterization of Evacuated Tube Collector Solar Water Heater with Constant Inlet Water Temperature

Abstract: With large evolution in the solar technology, research is turned out to be more sophisticated. Evacuated tube collectors (ET Collectors) are the most eco-friendly and efficient solar water heaters used worldwide. A series of experiments have been performed on ETC Characterization System. The research presents the evaluation of the performance of an ET Collector and characterize the solar water heater at different wind velocity of (2, 3, 4 m/s) and solar radiation between 250 to 750 W/m2 by keeping temperature of inlet water as constant. Examining the system performance at different temperature of inlet water of (29 °C, 40 °C, 50 °C). Net heat loss through evacuated tubes (ETs), heat loss coefficient through ETs, & the efficiency of an ET Collector has been recorded.

Modeling and Simulation of Indirect Collector Solar Hot Water Heating System Based on TRNSYS

The use of solar energy is one of the important ways of clean energy heating in rural areas in the north, and the collector solar water heating system is an effective way to use solar energy. This paper takes a typical single residential house in a rural area of Shenyang as a research case to design an indirect collector solar hot water heating system. Based on the meteorological data of the winter heating period (November 1 - March 31 of the following year) in Shenyang, TRNSYS software was used to research the heat collection efficiency and scheme design of the heating system. The research results showed that: 1) The best material of the heat exchange coil of the hot water storage tank in the solar water heating system of the indirect collector is stainless steel with a thickness of 0.8mm; 2) The optimal installation angle of solar collectors in Shenyang is 55°; 3) The optimal area of the heat exchanger coil in the hot water storage tank is 4.40m2.

Analysis of outlet temperature of parabolic trough collector solar water heater using machine learning techniques

The green sources of energy are ocean, hydro, solar, tidal, wave, wind, biomass, etc. Among all these wind, solar and hydro are mainly used. Particularly, solar energy has various applications such as atmospheric energy balance studies, solar energy collecting systems, analysis of the thermal load on buildings, etc. Parabolic trough collector (PTC) based solar water heater (SWH) gains a significant role in water heating systems. Parabolic trough collector is a concentrating type collector which collects the solar radiation in copper tube placed in the focal point of the parabolic trough. It also generates a high temperature which is suitable for steam generation. The main goal of this paper is to predict the outlet temperature of parabolic trough collector solar water heater with time and temperature for different days using various machine learning techniques.