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The performance of single slope solar still with an enhanced condenser at different saline water mediums in the basin is studied and assessed based on productivity, energy, exergy, economic, and enviroeconomic methodologies. Six solar still configurations are considered: conventional solar still (CSS); modified solar still (MSS) which is a still with heat sink condenser; MSS having an umbrella (MSS + U); MSS with forced-air cooling (MSS + FA); MSS with forced-water cooling (MSS + FW); and finally, MSS with forced-water cooling and contains sand in the basin (MSS + FW + SD). Experiments are conducted under hot and cold climate conditions of Sohag city, Egypt. The results indicate that the MSS + FW + SD has a maximum daily yield of 5.37 kg/m2 in summer and 2.74 kg/m2 in winter with an increase of 36% in summer and 26% in winter compared with CSS. It was found that the maximum increase of the energy and exergy efficiency compared with CSS is achieved in the case of MSS + FW + SD of 39% and 33%, respectively. Furthermore, the maximum and minimum cost of freshwater is achieved in cases of MSS + U and MSS + FW + SD, respectively. Finally, among all studied systems, MSS + FW + SD achieves the best performance based on the exergoeconomic approach. [ABSTRACT FROM AUTHOR]

• Using HSC and FW increases daily still productivity of CSS + PTC in summer by 24.7%. • MSS + PTC + FW achieves maximum energy efficiency of 19.4. • MSS + PTC + FW achieves maximum exergy efficiency while CSS + PTC has the minimum. • MSS with PTC has the minimum freshwater cost while MSS + PTC + U has the maximum. • MSS + PTSC achieves the best performance-based exergoeconomic approach. This study experimentally investigates the performance of solar still coupled with a parabolic trough solar collector (PTSC) at different cooling rates based on energy, exergy, exergoeconomic, and enviroeconomic standpoints. Different solar still systems are considered; conventional solar still (CSS), solar still with heat sink condenser (MSS) and coupled with PTSC (MSS + PTSC), MSS having an umbrella and coupled with PTSC (MSS + PTSC + U), MSS with PTSC and condenser forced air cooling (MSS + PTSC + FA), and MSS + PTSC with condenser forced water cooling (MSS + PTSC + FW). Experiments are conducted under hot climate conditions of Sohag city, Egypt. Results indicated that the freshwater yield of all studied systems in ascending order is as follow; CSS + PTSC, MSS + PTSC + U, MSS + PTSC, MSS + PTSC + FA, and MSS + PTSC + FW in summer with value of 7.74, 8.02, 8.68, 9.11, and 9.45 kg/m2, respectively. The maximum exergy efficiency of 1.34% in summer is achieved in case of MSS + PTSC + FW system. The economic analysis shows that distilled water cost is minimum for MSS + PTSC + FW (~0.02 $/L), while it is maximum for MSS + PTSC + U (~0.022 $/L). It can be concluded that high freshwater production and less distilled water cost are making the enhanced solar desalination system feasible and competitive. Minimum exergy efficiency occurs in case of CSS + PTC with a value of 1.197% and MSS has higher average daily exergy efficiency. MSS + PTSC achieves the best performance-based exergoeconomic approach. MSS + PTSC + FW is by far the best system in cutting down CO 2 emissions. [ABSTRACT FROM AUTHOR]

Solar air heating (SAH) is a low-cost method for air heating using solar energy. An energy and exergy performance is performed experimentally on new designed tubular SAH having tubular absorber of adjacent tubes forming flat pack. Each tube of the absorber contains three adjacent internal tubes forming nabla shape (∇). The nabla tubular SAH (∇TSAH) performance is studied compared to ordinary tubular SAH (OTSAH) having tubular absorber only for single pass (SP) and double pass (DP) flow conditions and different mass flow rates of air (MFRA). The study is investigated under upper Egypt hot climate conditions and 0.018–0.081 kg/s MFRA. The results demonstrate that ∇TSAH has higher outlet air temperature, energy gain, higher energy, exergy, and thermohydraulic efficiencies, and lower top losses than the OTSAH. The new design boosts the exit air temperature by about 13.5 and 5 °C for SP and DP, respectively compared to OTSAH. Moreover, it enhances the energy efficiency by about 28.1% and 71.5% and the exergy efficiency by about 56.2% and 76.8% compared to OTSAH and flat plate SAH (FSAH), respectively at 0.027 kg/s. The maximum ∇TSAH output net energy gain is achieved at 0.072 kg/s for SP and 0.036 kg/s for DP. [Display omitted] • Energy and exergy of new designed Nabla-shaped SAH are investigated experimentally. • Maximum outlet air temperature rise is 50.2 °C for ∇TSAH and 36.7 °C for OTSAH. • ∇TSAH performance is greater than that of OTSAH and the latter is greater than that of FSAH. • Average daily energy efficiency is 88.4% for ∇TSAH, 77.3% for OTSAH, and 72% for FSAH. • Average daily energy efficiency is 3.89% for ∇TSAH, 2.49% for OTSAH, and 2.2% for FSAH. [ABSTRACT FROM AUTHOR]

There has been a theoretical investigation for energy, exergy, and economic evaluation of thermal regulation of PV panels via an innovative hybrid cooling system of flat heat pipes (HPs) coupled with phase change material (PCM). PV panel dissipates its heat through the HP evaporator while the HP condenser is cooled by PCM. The cooling system performance is investigated for different PCM quantities and types (RT42, RT35HC, and SP31) for summer and (RT21, RT18HC, and SP15-gel) for winter conditions in Egypt. A thorough study and analysis have been conducted for the impact of the cooling system on PV panel's temperature, electric efficiency, output power, PCM energy storage, and system efficiency. The results show that compared with conventional PV, the best PCM type for PV performance in summer is SP31 of 3 cm thickness, which achieves a maximum PV temperature reduction of 20.6 °C with a maximum improvement in PV electric efficiency of 11.5%. SP15-gel of thickness 2.5 cm is the best PCM for winter conditions, achieving 14.1 °C temperature reduction with 7.2% enhancement in PV electric efficiency. The exergy efficiency of the PV panel is higher than in PCM, where it rises as the phase change temperature of the PCM increases. PV maximum average daily exergy efficiency is 13.4% for SP15-gel, compared with 12.71% for conventional PV in winter, while SP31 achieved 12.25%, 1% higher than reference PV in summer. PCM's maximum average daily exergy efficiency is 0.69% and 0.7% for RT42 and RT21 in summer and winter, respectively. The minimum payback period for conventional PV is about 18.01 years, while it is approximately 13.39 years for PV with HP and PCM. The studied cooling system at different PCMs proves its capability to enhance the PV performance with higher energy and exergy efficiencies and lower cost and store the excess heat inside the PCM. [Display omitted] • Energy, exergy, and economic assessment of PV/HP- PCM cooling system is studied. • The impact of PCM type and quantity is considered at different climates conditions. • 20.6 °C and 14.1 °C PV temperature reductions were achieved using SP31and SP15-gel, respectively. • The exergy efficiency of the PV panel is higher than that of PCM. • HP-PCM cooling system efficiently regulates PV operating temperature at a lower cost. [ABSTRACT FROM AUTHOR]

An assessment of hybrid solar desalination system consists of solar panel integrated with single slope solar distiller improved by salty water preheating and porous material via productivity, energy, exergy, exergoeconomic and exergoenvironmental is performed under metrological conditions of Alexandria, Egypt. Water preheating is performed by passing it over the solar panel front surface before it enters the still basin, which is also used as solar panel cooler. The panel integration is performed by installing it directly over the still back wall. Solar panel power is used to heat up further the salty water. Moreover, the impact of utilizing black steel wool fibers in the still basin on the system performance is studied. Results illustrate that preheating 40%, 50%, and 60% of the salty water rises solar desalination system freshwater yield by 10.4%, 15.5%, and 20.9%, energy efficiency by 8.2%, 13% and 20% and exergy efficiency by 26.86%, 33.51%, and 60.64%, respectively. Using black steel wool fibers increases conventional solar still and solar desalination system production without and with 60% preheating by 17.8%, 13.7%, and 11.8%, energy efficiency by 13.58%, 9.73%, and 13.5% and exergy efficiency by 16.51%, 10.27%, and 32.45%, respectively. Solar desalination system with black steel wool fibers and 60% of water preheating achieves the highest performance based on freshwater yield, cost, energy payback time, exergoeconomic, exergoenvironmental and exergoenviroeconomic parameters. With these positive results and the available solar energy in Egypt, the current system can be a promising nation strategy in saline water desalination and power production. - Preheating 60% of the salty water rises freshwater yield by 20.9% compared to solar desalination system without preheating (0%). - Using BSWF increases freshwater yield of the system without preheating (0%), and with 60% preheated water by 13.7%, and 11.8%, respectively. - Preheating 60% of saline water, enhances energy and exergy efficiency without preheating (0%) by 20% and 112.8%, respectively. - System with BSWF and 60% preheated has minimum freshwater production cost and system without preheating (0%) has the highest. - SDS+BSWF (60%) migrates the maximum amount of CO2 based on environmental and exergoenvironmental of values of 27.98 and 2.2896 tons, respectively. [ABSTRACT FROM AUTHOR]