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Electric Injera baking Pan are prevalent in Ethiopia but are highly inefficient, resulting in significant heat loss, high energy consumption, and increased energy bills. This research investigates improving these devices using steel powder as an additive and gypsum as an insulator. The study examines thermal conductivity, baking time, energy consumption, heat loss, and insulation effectiveness. The objectives of this research are to improve the thermal conductivity of the baking surface while ensuring even heat distribution, enhance the insulation properties of the pan to reduce heat loss, improve the safety of the user by reducing the risk of excessive heat exposure to the outer surfaces, and reduce the overall energy consumption of the Injera baking process. Temperatures were measured using an infrared thermometer, digital thermometer, and thermocouple. Four samples (A0, A1, A2, & A3) with different steel powder compositions (0 %, 15 %, 25 %, and 35 %) and a constant 75 % clay soil composition were tested. The analysis showed an average baking energy of 0.45 kWh per kg of injera (0.198 kWh per injera) and a thermal efficiency of 86.4 % when baking 4.395 kg of injera. The total heat energy loss was 1402.78 KJ (14.08 % of 10300 KJ input energy). The losses were distributed among the retained (92.17 %), the baking plate (3.95 %), the bottom enclosure (2.08 %), the side enclosure (1.04 %), and the cover lid (0.76 %).
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Currently, the generation of electrical energy in Cuba is supported by oil and natural gas. These sources, as it is known, are directly linked to large emissions of pollutants that are released into the environment. Therefore, it is necessary to search for new energy options that are directed towards sustainable development, allowing the preservation of natural ecosystems. Owing to the location and geographical characteristics of Cuba, it is necessary to assess the energy possibilities of the seas that surround it and to search for the most feasible areas to obtain energy from the sea temperature. This renewable energy source, in addition to being used to generate electricity, can also be used in derived technologies, such as desalination, refrigeration, and aquaculture. Hence, a dataset is presented with the calculation of the thermal efficiency for the exploitation of thermal energy from the sea, which is based on the thermal gradient between the sea potential temperatures between the shore and the level of depth being analyzed. Outputs of 27 years of daily data from the Copernicus Marine Environmental Monitoring Service (CMEMS) GLOBAL_MULTIYEAR_PHY_001_030 product with a spatial resolution of 1/12° were used. The calculation was made using a Python script of the daily thermal efficiency at depths of 763, 902, and 1062 m, as these are the levels that are traditionally studied for the exploitation of sea thermal energy. In this way, 27 files of each level were generated for a total of 81 files in text format separated by commas. Each file is presented with the date, level, coordinates, and thermal efficiency. The dataset is available from the Science Data Bank repository ( https://doi.org/10.57760/sciencedb.10037).
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In this study, microemulsion synthesized from chemically extracted Salvinia molesta oil with diesel was evaluated as fuel in stationary unmodified diesel engine. The microemulsions from S. molesta oil was prepared using the best combinations of 67% S. molesta oil, 15% ethanol, 13% water and 5% surfactant (span 80) and its properties were compared with that of diesel. The engine test conducted with M10, M20 and M30 blends and reported a brake thermal efficiency of 29.76% and brake specific fuel consumption of 0.3239 kg/kWh with M20. The emissions like NO and smoke reduced by 18.07% and 7.37%, respectively, with marginal increase in CO, CO2 and unburned hydrocarbon by 3.8%, 3.4% and 16.66% respectively, with M20 compared to diesel at maximum engine load of 3.73 kW. At lower engine loads with M10, M20 and M30 slightly lower CO2 emission than diesel. A drop in peak pressure and heat release rate was found to be 1.73% and 8.40%, correspondingly with M20, as that of diesel. Even though a slight reduction in brake thermal efficiency observed with M20 as compared to M10 and diesel by considering the lowest emissions of NO and smoke, it is feasible to use as promising fuel for unmodified diesel engines.
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Numerous research studies have found that a double-pass solar air heater (DPSAH) performs better than a single-pass solar air heater (SAH). This suggested study aims to evaluate the performance of a DPSAH setup in Southern Tamil Nadu, India. Several artificial roughness features have been incorporated into the solar black-coated absorber plate for this examination. Broken ribs with semi-circular and semi-polygonal shapes are used and explicitly tested on the absorber plate. Next, the efficiency of these rib designs is contrasted with a typical flat plate DPSAH. These studies also employ three different mass flow rates (0.01 kg/s, 0.02 kg/s, and 0.03 kg/s), enabling a thorough assessment of the DPSAH system's performance at each rate. These studies' findings demonstrate that adding artificial roughness to the solar collector plate has a beneficial effect on the turbulence of fluid flows. As a result, this innovation increases the double-pass solar air heater's (DPSAH) heat transfer rate. It is noteworthy that compared to the DPSAH with flat plates, both rib designs perform better. It is important to remember that the semi-polygonal ribs function better than the semi-circular ones. The average efficiency values for the semi-polygonal rib structure are 17.1%, 18.7%, and 19.1% greater than those seen for flat plates. These efficiency values are additionally 4.4%, 7.4%, and 8.7% higher than those attained with the semi-circular rib topologies at flow rates of 0.01 kg/s, 0.02 kg/s, and 0.03 kg/s, respectively. The study goes into considerable detail on how particular rib patterns can be advantageous economically and environmentally.
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Energía Solar , IndiaRESUMEN
The need to address global warming issues and international policies has placed a greater emphasis on the development of solar energy utilization systems. Intensive study is necessary to expand solar energy applications, as solar energy potential varies widely. This study investigates the thermal and thermohydraulic performance of a modified flat plate solar air heater (FSAH) to assess the effects of using corrugated aluminium duct and sand heat storage elements (HSE) in various combinations. The different arrangements selected for the experimental investigation are the FSAH, FSAH with corrugated aluminium duct (FSAH-C), FSAH with a sand heat storage element (FSAH-S), and FSAH with a combined use of corrugated aluminium duct and a sand heat storage element (FSAH-CS). The materials used for fabrication are low-cost and readily available in the study area. The results indicate that the sand bed enhanced the thermal performance by acting as the thermal heat storage medium, which could also supply heat for a short duration after non-sunny hours, and the corrugated aluminium duct enhanced the surface area and allowed the air to pass twice inside the SAH. We observed that the SAHs with sensible heat storage had a higher top loss compared to the FSAH-S configuration. The average thermal efficiency of the FSAH-CS configuration was 59.17%, which is 8.81%, 5.72%, and 10.95% higher than FSAH-S, FSAH-C, and FSAH, respectively. Furthermore, this configuration achieved an exit temperature of 64.5 °C. The proposed system has a thermohydraulic efficiency of 59.14%, which is not significantly different from the average thermal efficiency. Therefore, the suggested system verifies its ability to function without requiring substantial external power.
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Solar water heaters are a type of renewable energy technology that converts solar energy into heat to warm water. Solar water heaters are becoming increasingly popular due to their eco-friendliness, cost-effectiveness, and low maintenance requirements. In this study, low-cost solar collectors were developed using date palm waste (dried leaves) as thermal insulation. Date palm waste is a readily available and abundant resource in many regions, and using it in solar collectors can help reduce waste and promote sustainability. Two solar collectors were fabricated using crushed date palm waste, with one collector using the waste alone and the other mixed with starch. Tests were conducted in accordance with the European standard EN 12975-2-2006 and modeled the thermal behavior of the collectors. The results obtained showed that the prototypes of solar collectors performed well and exhibited behavior comparable to that of a commercial solar collector, with a production cost up to three times less. The use of date palm waste as thermal insulation in solar collectors is an innovative approach that aligns with the principles of sustainability and environmental friendliness. Furthermore, it was found that the leveled heating cost (LCOH) and the simple payback period (SPP) were 0.952 US$ kWh-1 and 2.472 years for the prototype without starch and 0.926 US$ kWh-1 and 2.397 years for the prototype with starch.
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Phoeniceae , Energía Solar , Agua , Almidón , Luz SolarRESUMEN
In this work, pebbles of higher specific heat than the conventional absorber materials like aluminium or copper are proposed as a absorber in the solar flat plate collector. The proposed collector are integrated into the building design and constructed with masonry. Tests were conducted by varying the operating parameters which influence its performance, like the flow rate of the heat-absorbing medium, and the tilt of the collector using both coated and uncoated pebbles. The maximum temperature difference that could be measured for a conventional absorber was approximately 8 °C for a flow rate of 0.6 L/min. While for a coated and uncoated absorber, it was 7 °C and 5.5 °C respectively. This difference decreased with an increase in flow rates from 0.6 L/min to 1.2 L/min. For all the flow rates, it was observed that the average difference in efficiency between the coated and the conventional absorber collector is 5.82 %, while the difference between the coated and uncoated absorber collector is 15.68 %. Thus, it is very much evident that by replacing the conventional absorber with the proposed coated pebble absorber, the overall loss in efficiency is just 5.82 %, but the advantages are enormous. Along with the experimental study, numerical analysis was also carried out with CFD modeling. The numerical results agreed well with experimental results with the least error. Therefore, CFD simulation can be further used to optimize the design of the collector.
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This paper aims to highlight the use of different heat transfer fluid (HTF) configurations based on vegetable oils in Parabolic Trough Solar Concentrator (PTSC). Rapeseed and jatropha oils as innovative heat transfer materials combined with SiO2 and Al2O3 to obtain six (6) HTF configurations are used in a 1-dimensional PTSC model. The thermophysical properties of the nanofluids are determined from correlations derived from the literature, using Gauss-Seidel method from a numerical code developed in Matlab software. Model validation is obtained. Thermal sensitivity analysis shows that the use of rapeseed increases the thermal efficiency of the PTSC by around 4.21 % compared with jatropha. The use of nanofluids reduces thermal losses within the system due to thermal gradients. For a fixed irradiance and each 1 %-4 % increase in volume fraction, thermal efficiency increases by around 1.96 % when Al2O3/rapeseed is used and by 0.47 % when SiO2/rapeseed is used compared with rapeseed. Similarly, thermal efficiency increases by around 1.98 % when Al2O3/jatropha is used and decreases by around 0.20 % when SiO2/jatropha is used compared with jatropha. However, the positive effects of nanoparticles on thermal conductivity alone are not always sufficient to improve thermal efficiency, and thermal effects on heat capacity should also be considered.
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Uneven drying is the key drawback of a conventional multi-tray dryer. Therefore, an improved active solar dryer with and without integrated sensible heat storage (SHS) was proposed. A unique feature of this dryer is its movable walls from the sides of the dryer to transform it to an indirect or mixed-mode as and when necessary. Garcinia Pedunculata (GP) is a local seasonal medicinal fruit in Northeast India. Drying kinetics of GP, the dryer performance and economic analysis of dryer were evaluated in the indirect solar dryer without SHS (Exp. I), mixed-mode solar dryer without SHS (Exp. II), indirect solar dryer with SHS (Exp. III), mixed-mode solar dryer with SHS (Exp. IV), and open sun drying (OSD). The dryer's average efficiencies were 18.12%, 22.37%, 21.74%, and 24.46% for Exp. I, Exp. II, Exp. III, and Exp. IV, respectively. The moisture content of GP was reduced to 12.09% in wet basis (w.b.) from 87.99% (w.b.). The overall drying time for Exp. I, Exp. II, OSD, Exp. III and Exp. IV were 31, 26, 53, 28, and 10 h, respectively. From the eleven drying models, the Two-Term model was the best-fitted model for Exp. I, Exp. II, OSD and Exp. III, and Midilli and Kucuk model was for Exp. IV. The final product's fragrance and colour are better for Exp. IV. Developing this dryer for Exp. I, Exp. II, Exp. III and Exp. IV, the price required was around 25,000, 27,000, 26,000, and 28,000 INR (1 US$ = 74.57 INR), respectively, while the economic payback periods are 1.6 years, 0.9 year, 1.4 years, and 0.59 year, respectively.
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Garcinia , Thoracica , Animales , Calor , Desecación , Luz SolarRESUMEN
The daily increase in the demand for energy consumption is partly caused by the global population explosion and advancements in technology. Humanity relies on energy to fulfil its daily routines, such as electricity for lighting, heating, cooling, and running electronic devices. There are continuous attempts by researchers and industry experts to optimize and enhance the efficiency of various sustainable energy generation devices. Solar collectors play a critical role in the renewable energy sector, which is vital in helping the world achieve a clean, green, and sustainable environment. Over the last two decades, researchers have made significant efforts to explore various techniques for enhancing the effectiveness of solar thermal collectors. Their effort has been centered around improving the fluid thermal properties, which act as the heat transfer medium in solar collectors. The discovery of nanofluids will help resolve some of the challenges associated with conventional fluid used in solar collectors. Enhancement through nanofluids is influenced by several factors, which include nanoparticle types, nanoparticle concentration, base fluid, and the purpose of its application. This review provides a technical summary of the application of nanofluids in the two main types of collectors: non-concentrating and concentrated thermal collectors. Findings from this study showed that TiO2 + Cu hybrid nanofluids with a mass fraction of 0.03 augment heat transfer coefficient by 21% in parabolic trough collectors. The merits of employing nanofluids as heat transfer fluids in solar collectors are examined, while also outlining the obstacles and areas where further research is needed.
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In this study, machine learning techniques, namely artificial neural network (ANN), support vector machine (SVM), and extreme gradient boosting (XGBoost), were used to comprehensively evaluate engine performance and exhaust emissions for different fuel blends. To obtain valuable insights on optimizing engine performance and emissions for alternative fuel blends and thus contribute to the advancement of knowledge in this field, we focused on iso-pentanol ratios while maintaining the biodiesel ratios constant. The maximum brake thermal efficiency (BTE) values for the diesel (30.13 %), D85B10P5 (29.92 %), D80B10P10 (29.89 %), and D70B10P20 (29.79 %) blends were achieved at 1600 rpm. At 1600 rpm, the brake-specific fuel consumption (BSFC) values for the diesel, D85B10P5, D80B10P10, and D70B10P20 blends were 189.93, 200.93, 202.93, and 203.95 g kWh-1, respectively. In engine performance prediction, the ANN model exhibited superior performance, yielding regression coefficient (R2), root mean square error, and mean absolute error values of 0.984, 0.411 %, and 0.112 %, respectively, in BTE prediction, and 0.958 %, 6.9 %, and 2.95 %, respectively, in BSFC prediction. In exhaust gas temperature prediction, the SVM model exhibited the best performance, yielding an R2 value of 0.981. Although all models successfully predicted NOx emissions, the ANN model exhibited the best performance, achieving an R2 value of 0.959. In CO2 and hydrocarbon estimation, the XGBoost model exhibited the best performance, yielding R2 values of 0.956 and 0.973, respectively. Therefore, the ANN model can be used to accurately predict engine performance, and the XGBoost model can be used to accurately predict emission parameters.
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This work proposes a novel transparent solar cooker design, and its performance is evaluated using a set of experiments. The cooker is fabricated from transparent and non-transparent, and lightweight material. The study was conducted at the Renewable energy laboratory in India (MNNIT Prayagraj). For thermal performance assessment of Box-type standard solar cooker with an inclined cover (BTSCIC) is compared with a box-type standard solar cooker (BSSC). The area, heat input, and thermal efficiency have all increased significantly. The total absorbing area increases by 32%, total solar radiation by 189%, absorber plate temperature by 19.8%, inner air temperature by 16.5%, pot water temperature by 17.1%, and inner wall average temperature by 58%, as compared to box-type Standard Solar Cooker. The average exergy was 4.2% (BTSCIC) and 2.61% (BSSC), respectively. The cost payback period of BTSCIC was 2.22 years and BSSC 1.5 years.
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Artículos Domésticos , Energía Solar , Calor , Productos Domésticos , IndiaRESUMEN
The waste-heat-recovery boiler with water injection (HR-B/W) applies the heat exchange between the intake air and exhaust gas with the water injection into the intake air. Previous theoretical studies have discussed that the HR-B/W would increase the thermal efficiency of the boiler by the active heat exchange between the intake air and exhaust gas. It has also been discussed that the increased fraction of water vapor in the air would reduce the flame temperature which in turn decreases the NOx emission. However, the potential performance of the HR-B/W has not been validated through practical boiler tests by considering the evaporation characteristics of the injected water, which plays a critical role in the performance of the HR-B/W. In this study the effects of water injection into the intake air on the thermal efficiency and pollutant emissions of the waste-heat-recovery boiler are investigated using a commercial 24 kW condensing boiler in full load condition. Thermodynamic analysis is performed to evaluate the adequate amount of water injection and trace the physical properties in the boiler upon the water injection amount and evaporation characteristics. The boiler test results showed water injection can increase thermal efficiency to 4.4% point and reduce NOx and CO emissions by 69% and 33% respectively compared to those without water injection. These advantages can be further enhanced if the atomization and evaporation performance of injected water is improved.
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This study investigates the thermal efficiency and exergy efficiency of a thermoelectric power generation device for recovering power cable surface waste heat. Numerical simulations are conducted to analyze the impact of different types of cooling fins on the system's performance. The results demonstrate that the installation of cooling fins improves heat transfer efficiency and enhances the thermoelectric power generation device's output power. Among the various fin designs, the system equipped with cooling fins with 17 teeth exhibits the highest performance. These findings highlight the importance of fin design in optimizing the system's thermal efficiency and exergy efficiency. This study provides valuable insights for the development and improvement of thermoelectric power generation systems for power cable surface waste heat recovery applications.
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This work aims to enhance the performance of a solar air heater (SAH) by introducing broken V-ribs as roughness elements on the absorber plate. The unit with a conventional flat absorber plate is referred to as the "FSAH," while the unit with a broken V-rib-shaped absorber plate is called the "VSAH." The experiment was performed for three air velocities: 25 m/s, 20 m/s, and 15 m/s and the corresponding air flow rates were 0.037 kg/s, 0.031 kg/s, and 0.023 kg/s, respectively. The results showed that the maximum temperature was experienced on the absorber plate, followed by the glass plate for both SAHs. Overall, the average absorber and glass plate temperatures of the VSAH were 0.6-1.4 °C and 0.4-1.9 °C lower than those of the FSAH. Compared to the FSAH, the experimental results showed that the VSAH experienced useful power and thermal efficiency that were 16.6-19.8% and 15.7-20.4% higher, respectively, while the top surface heat losses were found to decrease by 2.1-8.1%. Due to the disrupted air paths in the VSAH, the observed pressure drop was 113.3-133.3% higher than that of the FSAH. More impotently, the thermo-hydraulic performance factor was always higher 1 and the observed values were 1.48, 1.39, and 1.24 at the va (velocity) values of 15, 20, and 25 m/s, respectively. Therefore, the proposed VSAH had an admirable thermal performance as compared to FSAH. Further, optimization through varying the roughness parameters, namely, relative blockage width (W/w), relative pitch ratio (P/e), number of baffles (n), relative blockage height (e/H), and angle of attack (ß) could helped to achieve better performance.
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Energía Solar , Luz Solar , Temperatura , CostillasRESUMEN
The utilization of nanofluids and concentrating techniques in solar photovoltaic/thermal (PV/T) systems, to enhance the overall system performance, have been analysed explicitly in the last few years. More recently, nanofluid-based optical filters were integrated with photovoltaic (PV) systems for the effective utilization of solar spectrum, i.e. below and beyond the band-gap of PV cells. Therefore, to quantify the recent progress of spectral beam splitting-based hybrid PV/T systems (BSPV/T), a systematic review has been presented therein. The study highlights the technological and scientific advancement in BSPV/T in last two decades. Linear Fresnel mirror-based BSPV/T showed significant enhancement in the overall performance of hybrid PV/T system. Recently developed nanoparticle-laden BSPV/T system shows significant improvement in overall thermal efficiency of BSPV/T system, thanks to decoupling of thermal system and PV cell. Further, economic analysis, carbon footprint, and environmental assessment of BSPV/T are also discussed briefly. At the last, the authors have made an effort to identify the challenges, limitations, and prospective paths for future research in BSPV/T systems.
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Huella de Carbono , Nanopartículas , Estudios Prospectivos , TecnologíaRESUMEN
The rapid growth in the world-population urges the need for potable water in various regions, especially in hot and dry regions. The main challenge in the productivity of potable water is the cost and availability of water sources. Thus, it is crucial to develop effective methods to overcome this global need. Utilizing solar power is proven to be a promising path to implementing thermal solar radiation in solar distillation applications. This work investigates the effectiveness of using concentrated solar power to irradiate heat exchange to evaporate water in a receiver, which will be collected as pure water in a condenser later. The thermal performance of the proposed model and its productivity are tested experimentally by using tap water only, and the test was repeated twice using two nanofluids namely, (aluminium oxide (Al2O3) and zinc oxide (ZnO)). The results showed that using (Al2O3) has a superior influence on the productivity of the solar unit, where the productivity is increased by 43.53% and 21.89% when compared to tap water and zinc oxide (ZnO) nanofluid respectively. The thermal efficiency of the solar unit was also increased by 9.91% (maximum) when using (aluminium oxide (Al2O3) as a working fluid compared to tap water. The model has simple components and is easy to install with a compact size, which can be developed be utilized in urban and desert areas.
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Insulated concrete sandwich wall panels (ICSWPs) are gaining popularity as energy regulations become stricter worldwide. ICSWPs are now being constructed with thinner wythes and thicker insulation to keep up with the changing market, which is reducing material costs and increasing thermal and structural efficiency. However, there is a need for adequate experimental testing to validate the current design methods for these new panels. This research aims to provide that validation by comparing the predictions of four different methods with experimental data obtained from six large-scale panels. The study found that while current design methods adequately predict the behavior of thin wythe and thick insulation ICSWPs within the elastic region, they do not accurately predict their ultimate capacity.
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Biodiesel from Jatropha oil is produced through catalyzed homogeneous transesterification. Hydrogen peroxide (H2O2) is considered as additive. Blends of Jatropha considered in the present study are 60% diesel, (40-A)% biodiesel and A% additive, varying A from 0 to 10. Identifying optimal input variables (such as additive volume percentage, injection pressure, and load) is important for improving the engine performance and reducing emissions. Air-fuel ratio; brake specific fuel consumption (BSFC); and brake thermal efficiency (BTE) are the engine performance characteristics. Carbon monoxide (CO); carbon dioxide (CO2); exhaust gas temperature (EGT); nitrogen oxide (NOx); and smoke opacity are the emission characteristics. 27 experiments need to be performed for the assigned 3 levels and 3 input variables. The Taguchi's L9 orthogonal array (OA) is chosen to perform only 9 experiments to obtain the optimal solution. The expected range of performance characteristics and emissions was obtained following a modified Taguchi approach. Empirical relationships are developed and verified through engine performance and emission characteristics.
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Membrane distillation (MD) is a thermal-based membrane operation with high potential for use in the treatment of aqueous streams. In this study, the linear relationship between the permeate flux and the bulk feed temperature for different electrospun polystyrene membranes is discussed. The dynamics of combined heat and mass transfer mechanisms across different membrane porosities of 77%, 89%, and 94%, each with different thicknesses, are examined. The main results for the effect of porosity with respect to the thermal efficiency and evaporation efficiency of the DCMD system are reported for electrospun polystyrene membranes. A 14.6% increase in thermal efficiency was noted for a 15% increase in membrane porosity. Meanwhile, a 15.6% rise in porosity resulted in a 5% increase in evaporation efficiency. A mathematical validation along with computational predictions is presented and interlinked with the maximum thermal and evaporation efficiencies for the surface membrane temperatures at the feed and temperature boundary regions. This work helps to further understand the interlinked correlations of the surface membrane temperatures at the feed and temperature boundary regions with respect to the change in membrane porosity.