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Various gaseous pollutants are released by industrial and anthropogenic activities, and the quest to remove these pollutants from the environment is gaining attention recently to ensure the safety of living creatures. Among various technologies, adsorption offers distinctive advantages due to its low cost, low energy consumption, and simplicity for remediation. Organic base materials, such as activated carbon, are widely used as adsorbent materials, whereas inorganic adsorbent materials prove their potential for replacement because of their abundance, low cost, and simple modification. Review papers on the use of inorganic adsorbent materials for the removal of gaseous pollutants are uncommon. As such, this review presents the progress achieved in utilizing various inorganic materials and their modified forms as adsorbent for gas phase depollution and their limitations. Various modification strategies for competitive adsorption and specified pollutions to achieve improved performance are discussed to realize their wide application in the adsorption technology. Fundamental studies should be performed to decrease the knowledge gaps on the utilization, regeneration, and modification of inorganic materials for wide application as adsorbent for gaseous pollutant removal.

Air water-harvesting systems are considered important technologies for overcoming the global water scarcity issue. Various relative humidity and cost considerations make sorbent-based air water-harvesting systems the most desirable technologies among current air water-harvesting systems. The limited availability of commercial instruments for air–water harvesting systems indicates a lack of fundamental studies on this field. In this regard, this review paper discusses and presents progress in the fields of sorbent materials and condensation and system design and future considerations in accelerating the commercialization of these technologies. Particularly, bio-inspired composition and design, mix design systems, use of renewable energy sources, modification of available sorbent materials according to functionalization, and composites are factors that require further attention. Fundamental studies of sorbent stability and life cycle, water absorbency, adsorption kinetics, heat and mass transport, regeneration condition, water-collecting surface design, and system design are essential.

Device modelling of copper indium gallium selenide (CIGS) solar cell with tungsten di-suphide (WS2) as a window layer has been carried out in order to achieve higher conversion efficiency. Conversion efficiency for all band-gap energies of CIGS were calculated based on proposed new CIGS/WS2 structure. Numerical modelling tools were used to investigate the effects conduction band offset and interface defect state on the photovoltaic parameters of CIGS/WS2 solar cell. The model predicts the density of defect tolerance in the interface is 1 × 1011 cm3. Based on optimization, the highest efficiency of 26.4% has been achieved for CIGS/WS2 solar cell with Eg(CIGS) = 1.4 eV (Voc = 1.026 V, Jsc = 29.57 mA/cm2 and FF = 86.96%) which is better than that of CIGS (23.4%) solar cell. The simulation further identifies that proposed CIGS/WS2 structure is less temperature sensitive compared to conventional Si solar cell. This research paves the way for WS2 thin film as a potential window layer material for CIGS solar cells.

Aerogels with extraordinary properties have attracted much attention due to their suitability for different technologies. However, the drawbacks of aerogels, such as expensive raw materials and cos...

A study investigating the effects of titanium (Ti) atoms sputtered from different sources on substrate distance was attempted in order to effectively dope a reduced graphene oxide (rGO) thin film surface. Factors such as crystallinity, morphology, phase formation, light absorption, and surface chemical state of rGO-TiO2 were investigated. As a result, functional groups or chemical states revealed the presence of Ti-O-C in rGO-TiO2 nanocomposite after the sputtering process. The titanium source from the target was of Ti3+ species as determined using X-ray photoelectron spectroscopy (XPS). It was found that average sized Ti3+ ions of around 59.4 nm were incorporated into the rGO nanosheet. A customized Dye-Sensitized Solar Cells (DSSCs) device was fabricated with the photo-anode consisting of sputtered rGO-TiO2 nanocomposite. After optimization, the Ti target allocated with 10 cm-apart FTO glass-coated rGO nanosheet and 0.67 cm2 active area exhibited an ideal PCE of 6.60%, which is remarkably higher than the usual 5 cm sputtering distance the sample (1.90%) had achieved.

Vehicle cabin soak temperature is dire and in some cases is a life-threatening for any living organism trapped inside it. Also, it dictates the thermal comfort level upon entry, air conditioning (AC) load, and fuel consumption. This study is the first attempts to experimentally evaluate the impact of integrating a solar chimney (SC) on a vehicle exposed to direct sunlight in terms of its cabin soak temperature (CST), thermal comfort, AC power, and driving ranges. Therefore, outdoor thermal soak tests on two identical vehicles were carried out. The results confirmed a significant reduction of the soak cabin temperature, decreasing the cabin soak air temperature by 20.5 °C (max). This reduction can lead to a significant effect on the initial thermal solar loads, thereby exposure time to high temperature environment (thermal stress and anxiety) can significantly be reduced, while also enhance interior air quality, improve vehicle fuel economy, an 85% reduction in compressor power, increasing driving range by 26.25 km within the city drive cycle and 17.5 km on the highway cycle while operating the AC system, and reduce tailpipe emissions while preserving the integrity of the cabin's interior from cracking and fading. It can be concluded that the proposed strategy is able to achieve the highest cabin temperature reduction ever compared to other passive approaches.

Air pollution and water pollution are critical issues because they negatively affect ecosystem and human health, as well as affecting buildings and industries. Utilizing photocatalysts that rely on light irradiation to decompose pollutants is a promising solution to this issue. Geopolymers, when used as a green substitute for cement and other engineered materials, can be synthesized using different agricultural and industrial wastes. These materials exhibit synergies in the depollution process and can be regarded as cost effective and novel in the context of removing organic pollution from water and air to protect and improve the environment. Geopolymer catalytic performance is closely linked to the composition, microstructure, and preparation method of the geopolymer. This review investigates the types of geopolymers and catalysts and their corresponding preparation methods and performances. The limitations of these products and future works are also detailed.

Graphene-based materials with unique mechanical, chemical, and biological properties are important members of the carbon family and important materials in the fields of nanomaterials and nanotechnology for molecular sorption and separation. The most common graphene materials that have been widely studied are graphene, graphene oxide (GO), reduced graphene oxide (rGO), and graphene nanocomposites. Because of extensive research, significant development has been made in the preparation, synthesis, and modification of these materials that have been commonly introduced as effective adsorbents of organic and inorganic toxic contaminants. The accumulation of pesticides, herbicides, and pharmaceuticals, as well as dyes and heavy metals from municipals and industrial discharges and their by-products, can release hazardous compounds into water resources and the atmosphere. The adsorption of toxic pollutants and contaminants onto graphene-based nanomaterials have been widely investigated. Recent studies revealed that graphene, GO, rGO and their modified nanocomposites are potential adsorbents. Employing novel efficient graphene-based adsorbents have opened a venue to sustainable green remediation. This chapter discusses the latest graphene-based adsorbents fabricated for removal of varieties of contaminants and toxic solid and gaseous materials. Additionally, the significant effect of surface functionalization of these adsorbents was also studied.

The lift off point for Electric vehicle (EV) sales is expected in the very near future even with oil prices that stayed cheap last few years and still inexpensive nowadays. Therefore, EV purchasers require convenient access to nationwide public charging stations infrastructure. The aim of this study is to assess the role of existing roofs of fuel Stations in deploying solar assisted electric vehicle charging systems (SAEVCS), electric vehicles and solar energy in Malaysia. PETRONAS petrol stations (PS) nationwide of Malaysia are selected to install solar charging systems on their existing infrastructure as a case study. Hybrid PV-Grid charging system is evaluated under different modes of grid power capacities (0–40 kW). The techno-economic feasibility indices are determined by using HOMER simulation tool. It is found that the estimated net average roof area of all PETRONAS stations is (500 m2); it will be considered as a representative for the roof area of each PETRONAS station. The produced PV power capacity at each station is found 85 kW. Over 1121 stations until the end of 2015, total PV power capacity is 95 MW with a total annual green energy production of 136 GWh/year; and a total battery bank capacity of 255 MWh. Total CO2 emissions that can be avoided by the nationwide PV charging systems is 88,559 ton/yr. The results showed that PS-SAEVCS, integrated with limited grid power line of (10 kW) can accommodate up to 2.14% of the initial EV penetration. Taking advantage of the FiT program, the cost of the PV/Grid-10 kW system can be retrieved in 6.3 years whereas the residual period (14.7 years) from the program is a net profit income. The attractive outcome from this study is that SAEVCS can be exploited as a station-to-grid (S2G) technique which is a worthy alternative to vehicle-to-grid (V2G) technology at the early years of system installation (initial stage of EV deployment).

In this study, ZnxCd1-xS/CdTe solar cells were fabricated on commercially available indium tin oxide (In2O3: Sn or ITO) and fluorine doped tin oxide (SnO2: F or FTO) soda-lime glass (SLG) substrates by RF magnetron sputtering. Thin ZnxCd1-xS window layers with lower zinc (Zn) content in comparison to cadmium (Cd) were deposited by co-sputtering of ZnS and CdS targets concurrently by changing the radio frequency (RF) power of both during sputtering. CdTe thin films for the complete cells were also grown by sputtering with different thickness. Prior to fabricating the complete device, characterization for growth optimization of ZnxCd1-xS window layer and CdTe absorber layer was performed by utilizing Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Ultraviolet–visible spectroscopy (UV–Vis), Field Emission Scanning Electron Microscopy (FESEM) and Hall effect measurement system. Complete ZnxCd1-xS/CdTe solar cells were fabricated with the optimized growth conditions of window and absorber layers. The best cell fabricated on ITO coated SLG substrates showed an efficiency of 8.08% with significant open circuit voltage (Voc) of 882 mV.

Copper (Cu) and silver (Ag) are the potential dopants that could enhance p-type doping of polycrystalline cadmium telluride (CdTe) thin films to be used in CdTe based solar cells. In this work, the effect of doping concentration of Ag and Cu in both thermal and laser anneal process of doping to CdTe thin film solar cells’ electrical performance were investigated. CdTe thin films of 3 µm thickness were deposited using the close-spaced sublimation (CSS) process and subjected to Cu and Ag doping process through dip coating in copper (II) chloride (CuCl2) and silver nitrate (AgNO3) solution, respectively at different concentration range followed by either thermal or laser annealing. Thermally annealed CdTe thin films were treated in convection oven, whereas laser annealing was carried out by illuminating the samples with pulsed neodymium-doped yttrium aluminium garnet (Nd:YAG) laser at wavelength of 532 nm. Fabricated solar cells were electrically characterized by light current-voltage (J-V) and capacitance-voltage (C-V) measurements. J-V measurement demonstrates that Cu doped CdTe solar cells are having better electrical performance as compared to Ag doped ones. The effect of increasing dopant solution concentrations seems to have consistent trend with the increase of J-V parameters as identified in this work. C-V measurement shows that Cu doped CdTe films has higher doping capability with the highest acceptor concentration of 1.5 × 1014 cm−3 compared to Ag doped CdTe films of 8.1 × 1013 cm−3. In addition, laser annealing finds lower J-V performance and acceptor concentration of Cu and Ag doped CdTe solar cells with limitations in smaller process space for surface annealing as well as optimization.

CdS microcrystal, with sphere like morphology, was synthesised from the residue obtained after the chemical bath deposition (CBD) of CdS thin layers usually deposited for CdTe and/or CIGS thin film solar cells, specifically by recycling the chemical waste. The residue was collected and reused to deposit cadmium sulphide (CdS) thin films on glass substrate by thermal evaporation. The films were subsequently annealed in vacuum at 250 °C, 350 °C and 420 °C for 40 min. The structural and optical properties were characterized by XRD, SEM, and UV–Vis spectrometry. All the films were found to exhibit high transmittance (over 70 to 90%). The optical band gap energy was found to be in the range of 2.28–2.37 eV, which is very suitable to be used as buffer or window for CdTe or CIGS thin film solar cells.

The cabin soak temperature represents one of the biggest problems plaguing car owners during hot days. This is exacerbated due to limited shaded parking spaces and its high associated cost should one be available. This study intends to investigate the impact of available passive approaches on regulating car cabin conditions and evaluate the potential of solar reflective cover (SRC) for temperature reduction and fuel consumption. Four soaking temperature cases were tested i.e. Case I: using two identical cars simultaneously (internal solar reflective films (SRF) vs. Baseline); Case II: using one car at different times (with/without SRC); Case III: using two identical cars simultaneously (SRC versus internal SRF); and Case IV: using two identical cars simultaneously (with/ without SRC). Interior cabin parameters were monitored by HD32.3A during soaking and cooling tests to evaluate the cabin air temperature reduction and occupants’ thermal comfort. The study revealed that an Aluminum cover on the cabin glazing and roof (case II) is the most effective approach, as it significantly reduced the cabin air temperature (by 17.7 °C). In this study, the lower/upper cabin comfort temperature limits were found to be ∼25.5 and 27.15 °C, respectively, as per the Fanger model. The thermal comfort level (27 °C) was attained at minute 7 by the cabin with SRC, whereas the baseline car attained the thermal comfort at minute 14 in the cooling-down test of case II. Covering the whole cabin with SRC can significantly decrease car cabin temperature when parking, which makes it viable as a benchmark for other passive approaches.

Thermoelectric technology is a promising solution to recover waste heat from different resources. There are numerous researches in the literature that measure performance of thermoelectric modules (TEMs). A comprehensive review of research studies that classifies and expounds disparities between various thermoelectric power generation (TEPG) systems is still unavailable and therefore, this paper reviews major concerns on their designs and performances. Firstly, various main elements of TEPG systems, which affect the output power of TEMs such as stabilizer or heat exchanger, interface, contact pressure, insulation, cooling system, and integrity are studied. Secondly, performances of test rigs and various prototypes are reviewed in detail based on their cooling methods since cooling is the most prominent factor among other counterparts. In general, the cooling unit is divided into either passive or active cooling system, which is selected based on its well-defined use. A comprehensive study on various test rigs with active cooling systems is given while a broader range in prototypes is covered and classified under detailed surveys. This review is expected to be of value for researchers in the field of thermoelectric. Overall, in order to have a prospective future towards commercialization of TEPG systems, the existing prototypes in the literature are still subjected to many enhancements in their design aspects, while further improvements are needed to be achieved independently in TEMs’ development.

This paper reports the energy and exergy performance of a photovoltaic/thermal solar-assisted heat pump system (PV/T-SAHPS) with different solar radiation levels. From the heat pump, the solar evaporator/collector extracts the thermal energy required, while the cooling effect of the refrigerant reduces the working temperature of the PV cells. Therefore, this integrated PV/T-SAHPS exhibits a relatively high thermal performance with improved coefficient of performance (COP) and PV efficiency. The Engineering Equation Solver tool embedded with the Hottel–Whillier equation was used to stimulate the system to quantify the enhancement of heat transfer due to the use of a refrigerant (R134a). Simulation results indicated that the maximum efficiency of the hourly electricity generation of the PV system could reach 11.56% at 1000 W/m2, the average electrical efficiency was 11.88%, and the maximum efficiency of the hourly thermal generation was 88.68% when the solar irradiance variation ranges from 300 to 1000 W/m2. The maximum PV panel temperature was 35.68 °C at 14:00. The average values of COP and COPex were 6.14 and 1.49, respectively. These result indicated that the heat pump system performance is relatively high.

It is difficult maintaining a minimum water depth in a conventional basin type solar still, as the required area is quite large. To overcome this difficulty, the RD this represents 29% enhancement compared to before modification. Finally, based on the results of the evaluation parameters and the statistical test, the thermal performance of the proposed stepped solar still is considerably improved through the new modification.

The high temperature of PV modules is one of the major factors that affect the PV system performance. The PV/T collector is proposed mainly to recover the heat of the high PV module temperature using conventional working fluids (water/air). Nanofluids (NFs) would help enhance the heat transfer/heat removal. The effect of NFs on enhancing the electrical/thermal efficiency of the PV/T collector besides the fluid's outlet temperature were investigate theoretically and experimentally. Fluent simulation tool together with energy balance equations were used. Three rounds of analysis were performed. Firstly, the optimal design of “sheet and tube” thermal absorber was determined using water as the base fluid. Secondly, the PV/T performance aspects using three types of NFs (CuO, SiO2, and ZnO) and water, were compared. Thirdly, the life cycle cost analysis/profit gain were applied to examine the feasibility of the grid connected PV/T-NF. The results showed that the optimal design of the PV/T thermal absorber requires 11 rectangular tubes per module, and the optimal rectangular tube dimensions are 24 mm (width) and 15 mm (depth). The results also revealed that the NF-SiO2 showed outstanding enhancement compared to other types of NFs and water. In addition, the results revealed that using NF- SiO2 in the PV/T collector reduced the PV module temperature from 65 °C to 45 °C and increased the outlet temperature from 35 °C to 44 °C, leading to an electrical and thermal efficiency enhancement of 12.70% and 5.76% respectively at a solar irradiance of 1000 W/m2. Payback analysis and profit gain of grid connected PV/T- NF (SiO2) system, grid connected PV/T- water system, and (grid connected PV + solar thermal) system were found (8 yrs, 10218.137 $; 11 yrs, 5518.518 $; 15 yrs, 3816.873 $), respectively. This indicated that the grid connected PV/T-NF (SiO2) system is economically feasible compared to the other systems despite the additional initial cost of the expensive NFs and the customized heat exchanger.

In this work, cadmium telluride (CdTe) thin film was deposited in vacuum (pure argon ambient) as well as different argon (Ar) and oxygen (O2) ambient conditions using close-spaced sublimation (CSS) method at the deposition pressure of 1 Torr. The deposited films were characterized via X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), UV–Vis spectrophotometer and Hall Effect measurement for the analysis of structural properties, morphology, optical properties and electrical properties, respectively. XRD patterns exhibited almost similar preferential orientation plane at (1 1 1) irrespective of the O2 concentration. SEM surface morphology microstructure revealed that O2 presence had a substantial effect on grain size reaching up to 7.19 µm. Optical properties also demonstrated insignificant changes in the direct band gap values of around 1.48 eV. Carrier concentration showed an upward trend in the order of 1013 cm−3, whereby resistivity and mobility did not change substantially either in vacuum (pure Ar ambient) or in Ar/O2 ambient.

This paper deals with the experimental investigation outlet temperature and efficiency, of Solar Air heater (SAH). The experimental test set up designed and fabricated to study the effect of jet impingement on the corrugated absorber plate, through circular jets in a duct flow of solar air heater, and compared with conventional solar air heater on flat plat absorber. Under effect of mass flow rate ( m ) of air and solar radiation on outlet air temperature, and efficiency, are analyzed. Results show the flow jet impingement on corrugated plat absorber is a strong function of heat transfer enhancement. The present investigation concludes that the mass flow rate of air substantially influences the heat transfer on solar air heaters. And the thermal efficiency of proposed design duct is observed almost 14% more as compare to the smooth duct. At solar radiation 500–1000 (W/M 2 ), 308 K ambient temperature and 0.01–0.03 (K g /S) mass flow rate

Solar technology is a promising renewable option and essential towards a sustainable energy future. PV power systems represent a major part of solar technology. The efficiency of a PV module is limited by many factors such as ohmic losses between solar cells, solar radiation, high module temperature, dust and packing factor. A combined PV/T concept was proposed to reduce the thermal stress of PV module by recovering the heat of high PV module temperature and use it for thermal applications. After decades of continuous research and development (R&D) aspects on PV/T, many researchers reported lower PV electrical efficiency, lower thermal efficiency and lower PV/T efficiency for it than the two separate systems. That is why, the product reliability of the PV/T system does not succeed in penetrating the market due to technical, cost and size barriers such as materials, design, manufacturing techniques, initial cost, installation cost and the bulk size of the system. Since the PVT concept failed to increase the electrical and thermal efficiencies concurrently, it would be more appropriate if the R&D community refocuses its efforts again on the heat dissipation option instead of the costly heat recovery option to regulate the high PV module temperature. The aim of this review is to provide an insight into the role of passive and active techniques in the thermal regulation of PV module temperature. The study will shed light on the temperature reduction range that is possible by the available passive and active heat dissipation approaches. Also, the effectiveness of passive approaches in lowering the temperature of the PV module when compared to active approaches will be highlighted as well. In addition to this overall study, this review will include a discussion of the effectiveness of passive and active approaches in the context of PVT collector, thus supporting the argument towards the potential of passive approaches when compared to active approaches. The outcomes of this study are detailed in the lessons-learned section and future research priorities are highlighted in the conclusion section.

Optimized synthesis of nanoparticles (NPs) increased the production of ultrapure and perfectly spherical NPs with small(er) average sizes. Many methods have been reported in the literature for synthesizing NPs, with sizes of 0.01–310 nm. Laser ablation is a well-known NP preparation method. It is regarded as a physical method that needs to be carried out in a controlled setting to obtain ultrapure NPs. Most studies on laser ablation involve the preparation of many types of NPs via the utilization of multiple targets. Since laser pulse parameters, laser focusing parameters, and the medium of ablation are essential factors influencing the synthesis of NPs (size, shape, and distribution), this study comprehensively reviews their effect to classify and organize them for use by interested researchers.

Increasing growth of the petroleum industry has resulted in huge amounts of various waste materials, which need proper disposal and valorization. The complexity, slow rate, and high cost of various remediation methods for wastes from the petroleum industry and the potential of utilizing these wastes in construction sectors have attracted huge attention. To select the best utilization option for petroleum industry wastes, the composition, microstructure of waste materials, and their influence and mechanism on the targeted construction materials must be clarified. Such data may help researchers predict the physical and chemical properties of newly developed formulations and tailor them based on their required composition by using optimum admixture components and additional treatments. Despite research on the utilization of petroleum waste materials in the construction industry, they are relatively incremental and limited in scope and need more scientific attention considering the composition, structure, influence of various components on one another in admixture formulation, preparation mechanism, effect of treatments, eco-friendliness, and cost efficiency. This paper provides an overview on the utilization of various petroleum waste materials in construction sectors and provide some directions for future research.

Silicon wafer-based solar cell contributes to about 92% of the total production of photovoltaic cells. An average of 30% of the incident light is lost via reflection from the front surface of the silicon solar cell, thus reducing the cell's power conversion efficiency. Texturization is a process of producing the desired unevenness on the surface of solar cell. It is well known as a practical solution to the limitation. Front surface texture reduces cell reflectivity and contributes to more photocurrent generation within active materials. The research and development efforts to reduce the optical losses via texturization are reviewed in this paper. The mechanisms of optical loss reduction, desirable texture feature, methods of texturization, side effects of texturization, and its compatibility with other optical enhancements for crystal silicon cell are elaborated upon. Front surface texture is associated with minimizing optical loss, and negatively affecting carrier and electrical losses. The importance of texturization for crystalline silicon is briefly related with thin film amorphous silicon solar cell to fully encompass this topic. Lesson learned and conclusion is highlighted in the last section.

The accumulation of dust pollution on the photovoltaic (PV) module can have a significant effect on the productivity and efficiency of PV systems in different locations in the world. Dust which accumulated over time on the PV module and is based on weather conditions led to the reduction in the effectiveness of solar cells. The aim of this research was to experimentally investigate the effect of the natural dust and the effects of environmental parameters on PV performance. The experiments were conducted to propose a model for the current, voltage, power and efficiency and to simulate the effect of environmental parameters on PV performance. The natural dust investigated consisted of different compounds: SiO2 (45.53 %), CaO (24.62 %), Al2O3 (10.83 %), Fe2O3 (10.46 %), MgO (6.33 %), K2O (0.87 %), TiO2 (0.45 %), SO3 (0.24 %), MnO2 (0.21), Cr2O3 (0.23 %), SrO (0.13 %) and NiO (0.09 %). It was found that the most accurate correlation is a polynomial from seventh degree for current, voltage, power and efficiency, fourth degree for solar radiation and temperature, cubic degree for humidity and wind velocity. The coefficients of general model are 0.6343, 0.0110, 0.0 and 0.0001 for PV module, respectively, with 0.0011 fitting factor. The proposed model has been validated using models in the literature.

Small-scale brackish water reverse osmosis (BWRO) desalination units are not a major commercial success compared to its large-scale counterpart. Integrating renewable power systems with small-scale units would theoretically aid in their deployment and subsequent commercial success. In fact, RO units are constructed using a modular approach; this would allow them to adapt to a renewable power supply. Small-scale PV-RO would be a promising form of desalination system in remote areas, where BW is more common. The aim of this study is to quantify the effect of climatic-design-operation conditions on the performance and durability of a PV-BWRO desalination system. A small-scale unit is designed, constructed, and tested for 6 months. The design was limited to a 2 kWp PV power system, five different membranes, a feed TDS of 2000 mg/l, and a permeate TDS of less than 50 mg/l. Data pertaining to solar radiation and temperature were subsequently analyzed to determine their respective influences on current and future operations of the unit. The results showed that the optimum RO load, membrane type, and design configuration were 600 W, (4″x40″ TW30-4040), and a two-stage configuration, respectively. The PV system was able to supply the load without any significant disturbances; while the RO unit showed stable levels of permeate flow and salinity. Operating the PV-BWRO system for 10 h during the day would produce 5.1 m3 of fresh water at a specific energy of 1.1 kWh/m3. It was confirmed that there are many hours of high temperatures during the operation of the PV module (exceeding 45 °C) and battery room conditions (exceeding 35 °C), both of which could negatively affect the power output and battery autonomy. This negative effect is compounded annually; therefore, optimizing thermal regulation of PV modules and battery bank room conditions is essential in maintaining excellent operating temperatures.

Combining the ejector-flash tank with the single stage absorption cycle has shown potential improvement in the COP. However, the cycle is still subject for further enhancement. Addition of two ejectors in the cycle to work under low-pressure of evaporator and intermediate-pressure of flash tank could optimize the COP of the cycle. In this study, the effect of adding two ejectors has been investigated. Moreover, a new stream line between 2 nd ejector and the rectifier has been created and evaluated. Energy balance analyses of the cycle before and after modification have been carried out. A computer simulation program has been developed to evaluate the performance of the cycles using ammonia–water solution as working fluid, operating under steady-state conditions. The results indicated that the overall COPs increment of the modified cycle are 11.56%, 12.42%, 13.46% and 14.05% at generator temperature of 80 °C, 85 °C, 90 °C, and 95 °C respectively. The results also showed that utilizing a part of streamlines of 2 nd ejector decreased the heat power in the generator and hence increase the COP. Generator and condenser thermal loads after modification are found permanently less than that in the cycle before modification which indicates a significant enhancement of the proposed cycle. The results showed also that the proposed cycle is able to work under higher operation temperatures as same performance as the cycle before modification (with one ejector) under lower operation temperatures. So, this investigation could help to promote absorption cooling systems in locations of high temperature conditions.

PV/T technology attracted numerous researchers and professionals during the last decades. There are many review papers in the literature evaluated the R&D aspects of PV/T collectors. In fact, there are abundant of case studies discussed the parameters of climate, design and operational conditions affected the PV/T collector performance. But, a comprehensive compilation of the information of those case studies is still a missing link in the literature. Hence, this paper intended to review thoroughly the information regarding the parameters affecting the PV/T collector performance mainly and PV module performance partially. The parameters are supported with the most available R&D to measure the accurate influence of each parameter on the performance. The outcomes from the study are highlighted in lessons learned section.

Combining the ejector–flash tank with the single stage absorption cycle using NH 3 /H 2 O as the working fluid has shown potential improvement in the COP. In our previous work, ejector efficiency faced some limitation due to the presence of booster at refrigerant streamline side. Removing the booster from the refrigerant streamline side and allowing the secondary flow of the ejector to work only under the intermediate pressure of the flash tank could optimize the ejector efficiency. This study examines the effect of system parameters, such as an entrainment ratio ( ω ), pressure ratio (PR), circulation ratio (CR), and the effectiveness of heat exchangers on the thermal loads, the coefficients of performance (COP c , COP), and the efficiency ratio ( η ) at various operating temperatures of the components. The study also discussed the effect of the operating conditions of the proposed cycle components on the performance parameters and the CR value in details. Comparing the results between the proposed cycle and our previous work showed that the new arrangement of the refrigerant streamline side increases the energetic secondary flow and consequently improved ejector efficiency. Moreover, the results showed that the thermal loads decrement of the generator and the absorber with SHE effectiveness increment is about 38% for each; while the thermal loads increment of evaporator and absorber with RHE effectiveness increment is found 14.86%, and 8% respectively. The performance increase ratio at maximum heat exchanger effectiveness is found 60.7% for SHE and 14.86% for RHE. Overall, the proposed cycle is considered beneficial from the viewpoint of the first law of thermodynamics.

In this study, an indirect forced convection solar drying system was tested for drying of palm oil fronds. The drying of 100 kg of palm oil fronds via solar drying system reduced the moisture content from 60% (w.b) to 10% (w.b) in 22 h (3 d of drying). During the drying process, the daily mean values of the drying chamber inlet temperature, drying chamber outlet temperature, drying chamber air temperature, and solar radiation ranged from 26 °C to 75 °C, 25 °C–65 °C, 26 °C–67 °C, and 96 W/m2 to 1042 W/m2 respectively, with corresponding average values of 53 °C, 46 °C, 48 °C, and 580 W/m2. At average solar radiation of about 600 W/m2 and air flow rate 0.13 kg/s, the collector, drying system and pick-up efficiencies were found about 31%, 19% and 67% respectively. The specific moisture extraction rate (SMER) was 0.29 kg/kWh. The exergy efficiency varied between 10% and 73%, with an average of 47%. In addition, the improvement potential of solar drying system for palm oil fronds ranged from 8 W to 455 W, with an average of 172 W.

In this study, the effects of vacuum annealing on the structural and electrical properties of DC-sputtered molybdenum (Mo) thin films have been investigated. Mo thin films were deposited by DC sputtering and subsequently subjected to vacuum annealing in a tube furnace from 350 to 500 °C. Films that were deposited with different temperatures showed good adhesion with soda lime glass substrate after “tape testing”. X-ray diffraction (XRD) spectra have indicated existence of (1 1 0) and (2 1 1) orientations. However, I (1 1 0)/ I (2 1 1) peak intensity ratio decreased for all vacuum annealed Mo films compared to as-sputtered films indicating change of preferential orientation. This suggests vacuum annealing can be employed to tailor the Mo thin film atomic packing density of the plane parallel to the substrate. SEM images of surface morphology clearly show compact and dense triangular like grains for as-sputtered film, while annealed films at 350 °C, 400 °C and 450 °C indicate rice-like grains. Stony grains with less uniformity were detected for films annealed for 500 °C. Meanwhile, electrical resistivity is insensitive to the vacuum annealing condition as all films showed more or less same resistivity in the range of 3 × 10 −5 –6 × 10 −5 Ω cm.

The heat transfer and flow characteristics in corrugated with V-shape lower plate using nanofluids are numerically studied. The computations are performed on uniform heat flux over a range of Reynolds number (Re) 8000–20,000. The governing equations are numerically solved in the domain by a finite volume method (FVM) using the k – e standard turbulent model. Studies are carried out for different types of nanoparticles Al 2 O 3 ,CuO, SiO 2 and ZnO with different volume fractions in the range of 0–4%. Three different types of base fluid (water, glycerin, ethylene glycol) are also examined. Results indicated that the average Nusselt number for nanofluids is greater than that of the base liquid. The SiO 2 nanofluid yields the best heat transfer enhancement among all other type of nanofluids. Heat transfer enhancement increase with increases the volumetric concentration, but it is accompanied by increasing pressure drop values. Moreover, the average Nusselt number increases with an increase in Reynolds number and volume concentration. The SiO 2 –glycerin nanofluid has the highest Nusselt number compared with other base fluids. The present study shows that these V-shaped wavy channels have advantages by using nanofluids and thus serve as promising candidates for incorporation into efficient heat transfer devices.

Energy conservation in building arena is essential issue for achieving sustainable environment. However, buildings experienced significant amount of heat gain or loss through window and this will affect the thermal comfort of buildings׳ occupants. Building without window is able to save energy, but it is not recommended due to the benefits of natural light on visual comfort and the biological effect of natural light on humans. Hence, window design plays important role in building architect. One of the essential parts of window is the glazing. Selecting a window glazing is complicated when energy saving and daylighting aspects of a building are considered concurrently. Optimization techniques offer a balance solution for the contradictions in selecting a window glazing of energy-efficient building. This paper intended to reveal the impacts of window glazing on the energy and daylighting performances of building through the previous researches. Then, the optimization techniques used by various researchers in choosing a glazing are highlighted. The emerging glazing technologies were discussed as well.

Previous works revealed that cross-corrugated absorber plate design and jet impingement on a flat absorber plate resulted in a significant increase in the performance of a solar air heater (SAH). Involving these two designs into one continuous design to improve the SAH performance remains absent in the literature. This study aimed to evaluate the achieved enhancement on performance parameters of a SAH with jet impingement on a corrugated absorber plate. An energy balance model was developed to compare the performance parameters of the proposed SAH with the other two SAHs. At a clear sky day and a mass flow rate of 0.04 kg/s, the hourly results revealed that the max fluid outlet temperatures for the proposed SAH, jet-to-flat plate SAH, and cross-corrugated plate SAH are 321, 317, and 313 K, respectively; the max absorber plate temperatures are 323.5, 326.5, and 328 K, respectively; the maximum temperature differences between the absorber plate and fluid outlet are ~3, 9, and 15 K, respectively; the max efficiencies are 65.7, 64.8, and 60%, respectively. Statistical t-test results confirmed significant differences between the mean efficiency of the proposed SAH and SAH with jet-to-flat plate. Hence, the proposed design is considered superior in improving the performance parameters of SAH compared to other designs.

In this paper, fully developed turbulent flow and heat transfer behavior in trapezoidal channels using nanofluids are numerically studied. This study evaluates the effects of four different types of nanoparticles, Al2O3, CuO, SiO2 and ZnO, with different volume fractions (0–4%) and diameters (20–80 nm) under constant heat flux (6 kW/m2). The effects of geometrical parameters (wavy amplitudes, longitudinal pitch) of the trapezoidal channel on the thermal and flow fields are also examined. The results indicated that SiO2 has the highest Nusselt number among the nanofluids. Enhancement of heat transfer increases with particle volume concentration, but a slight increase in pressure loss with decreasing nanoparticle diameter is also observed. When nanofluids are used in a forced convection, 10% increase in average Nusselt number is observed for nanoparticles with a diameter of 20 nm and at 4 vol.%. Analysis of the flow and heat transfer in a corrugated trapezoidal channel is made based on the comprehensive evaluation factor J/f. The optimum (J/f) enhancement shows that the CuO nanofluid, lower concentration ratio of nanoparticles, trapezoidal height of 2.5 mm and a longitudinal pitch of 6 mm are the most desirable parameters for saving energy. Using nanofluids with a corrugated channel can improve the thermal performance because it can lead to more compact heat exchangers.

Falling film heat transfer of horizontal shell-side evaporators remains of interest to scientists due to the complexity of these phenomena for practical applications. However, characteristics of heat and mass transfers of spray evaporators are still subject to further enhancement. This study is to review the enhancement techniques and falling film flow especially the effect of nanoparticles suspended with refrigerants in order to confirm their role. The study covers the influence of surface geometry (bundles and external of tubes), normal single tube, low fins, and enhanced geometrical tubes; effect of additives; and the applications and problems related to refrigerant-based nanofluids. Heat transfer area with energy related cost and the significant efforts on empirical correlations for heat transfer coefficient are discussed. It is found that the interaction of the heat and mass transfer process on falling film flow and contradictions of thermal physical properties of nanofluids should all be taken into careful consideration. In addition, existing research on both heat and mass transfer regarding nanofluids are found to be inadequate, and still requires extensive experimental and theoretical work on their salient parameters. Finally, this study highlights the factors affecting efficiency, compactness, and cost of the spray evaporator and the potential of enhancement techniques.

Malaysia's renewable energy (RE) feed-in tariff (FIT) (REFIT) is a new incentive for energy producers, the effects of which are unclear for investors. This study utilizes archival research method on existing Malaysian policies, plans, strategies, and action plans to present a comprehensive view of the solar aspect of the Malaysian FIT policy. This paper discusses Malaysia's REFIT scheme and the benefits of implementing the FIT policy in the solar sector. The Malaysian solar energy sector can preserve the country's oil and gas reserves, thus reducing carbon production and hindering environmental degradation. This paper examines the advantages and disadvantages of the Malaysian FIT model, and it concludes with an analysis of this design, with a focus on its implications for investors and for society. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 600–606, 2015

Many renewable energy policies are looking into new incentives to absorb investments by targeting abating CO 2 emission and fixing energy price fluctuation. Feed in Tariff (FIT) is a policy for rebating the amount of generated renewable electricity to investor. FIT is also defined as a CO 2 mitigation policy in electricity generation from renewable sources. This paper presents a cost benefit survey that estimates the real produced carbon dioxide for electricity generation in selected countries. This study introduces the substitute price of avoiding CO 2 emission as an indicator. The new indicator shows how much is paid for avoiding CO 2 by each selected countries through the FIT policy for renewable technologies. The amount calculated for solar energy is taken as a case in this paper. The result confirms that the FIT policy reasonably works for solar energy in absorbing investment. However the FIT policy claims a large portion of liquidity compared with other approaches. Hence makes this mechanism inept as a CO 2 mitigation policy.

Reasonable amounts of fresh water can be produced via inexpensive and sturdy solar stills in places that are exposed to solar radiation and have a brackish water. This work intends to analyze the many studies on factors that affect the performance of solar stills. The results showed that the distillation productivity of solar stills are significantly influenced by ambient conditions (e.g., ambient temperature, insolation, wind velocity, dust and cloud cover), operating conditions (e.g., depth of water, various dyes, salt concentration and inlet temperature of water), and design conditions (e.g., different passive/active designs of solar stills, slope of the cover, materials selection, storing materials, reflectors, insulation, gap distance and sun tracking system). It was also determined that the performance of solar stills was improved through the increase in solar radiation, ambient air temperature, wind speed, and water absorptivity. This also rings through with the decrease in water depth, thickness of cover, gap distance between water surface and condensing cover. It was also determined that both internal and external reflectors are capable of increasing the amount of absorbed solar radiation on the basin liner. The potential output of a basin type still can potentially increase to almost 70–100%. On top of this, the utilization of a sun tracking system was determined to be way more effective in improving the performance of solar still. This translate to the fact that solar stills being able to produce potable water at a very economical cost. Due to the existence of different methods of cost estimation, it is not possible to determine a universal, comparable price per technology; the cost per liter of distilled water obtained from the basin type solar still is ranged from 0.035 to 0.074$/liter. This study proved the fact that distillation productivity of solar still is heavily influenced by climatic, operational, and design parameters. Its output can be further improved via operational and design conditions, as climatic conditions are beyond our control.

Cadmium Telluride (CdTe) thin films were grown on borosilicate glass substrates by close-spaced sublimation (CSS) at a pressure of 1.5–2 Torr in Ar ambient. CdTe thin films were sublimed at a source temperature of 625 °C and substrate temperature of 595 °C. In this study, the impact of various deposition times on the structural, morphological, topographical, electrical and optical properties of CdTe thin films has been explored to achieve high quality thin film absorber layer for solar cells applications. The crystalline structure, surface morphology, surface topology, electrical and optical properties of the films were examined by using X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM), Hall Effect measurement and UV–Vis spectrophotometry, respectively. XRD investigation demonstrated that CdTe film shows polycrystalline nature pronounced with cubic zinc blende structure with a strong preferential (1 1 1) orientation. The FESEM images illustrated that the surface morphology and the average grain size of the films were dependent on the deposition times of CdTe thin films. AFM analysis revealed noteworthy changes in the film’s surface roughness values for different deposition times. Carrier concentration was found in the order of 1013 cm−3. Band gap of CdTe thin film was found in the range 1.45–1.48 eV, which is suitable to be used in CdTe thin film solar cells. Keywords: CdTe thin films, Close-Spaced Sublimation (CSS), Deposition time, Structural properties, Optical properties

A desiccant cooling system is among the best options to overcome future energy demand issues while considering human comfort by its ability to control both temperature and humidity. Although desiccant materials remarkably affect the performance of desiccant-based cooling systems, most studies focus on the design. This paper presents a review of the recent investigations on advanced desiccant materials regarding the improvement of the material properties for desiccant cooling application, emphasizing other important parameters, such as environmental conditions, cost, and design to achieve optimal performance. The preparation and performance of silica- and carbon-based desiccant materials are discussed. The current most suitable desiccant materials under different conditions for desiccant air conditioning systems and suggestions for future works are presented.

Water scarcity is a problem in remote locations, and producing fresh water in remote areas is an expensive process. The objective is to evaluate the optimum PV system to power BWRO desalination system that can produce 60m 3 /d at constant daily load profile for locations at different latitudes ranging from 60˚S to 60˚N worldwide. Different design configurations are simulated using ROSA software. Simulations showed that two-stage RO system is the better option with lower energy consumption. Hybrid optimization model for electric renewables (HOMER) is used to evaluate a range of equipment and design options over varying constraints and sensitivities in terms of sizing for the economic optimization of the PV power system. The minimum initial cost of the PV system is $102,000 and found at latitudes 50˚ S/N, while the maximum initial cost is $133,000 and found at latitude � 60˚. The economic performance of the PV system is then optimized under Malaysia latitude by allowing portions of the annual load to go unserved. The result shows that the optimum combination is a system with a 28kW PV array, 76 batteries, and 12kW converter with 1.5% annual unmet load fraction at 2˚ of PV slope. Allowing a small percentage of loads to go unserved throughout the year reduces the cost of the system. Powering RO system with PV power showed different initial cost for different latitudes.

The performance of a combined ejector-absorption cooling cycle has the potential for further investigation. Improving the performance of the system can be achieved by adding a flash tank to the combined cycle. In this study, an analysis based on the second law of thermodynamics is used to evaluate the cycle before and after modification. A mathematical model is developed to calculate the entropy generation in each component and the total entropy generation of the system, as well as to evaluate the exergy losses. Under operating conditions that match the ambient conditions and a certain application in Malaysia (Tgen = 85 °C; Tcond = Tabs = 30 °C; and Tevp = 0 °C), the coefficient of performance (COP) and exergetic efficiency (COPexe) values before and after modification are (0.844, 0.875) and (0.459, 0.476), respectively. The maximum exergy loss is found in the evaporator in both cycles, followed by the condenser and the absorber. A statistical t-test is carried out to establish the significance of the differences in the COP and the COPexe before and after modification. It is found that there is significant improvement in combined cycle performance after modification. Overall, adding the flash tank to the combined cycle can be considered a novel enhancement.

Low income households living in the rural areas suffer from energy poverty and lack of human and economic development. Currently, many governments of less developed countries are committed in improving access to electricity. The same commitment should be adapted globally as part of human right because providing electricity access to low-income households improves health and education, generates income, increases productivity, reduces inequality, and enhances the quality of life. Rural electrification is a complicated issue because of user affordability, rural inaccessibility and remoteness, low population densities and dispersed households, low project profitability, fiscal deficit, scarcity of energy resources, population growth, lack of professionalism, and over-dependence on subsidies. The demand for electrification cannot be accomplished because of the increasing gap between rural electrification rate and population growth. Therefore, this review aims to study various decentralized household-sized energy technologies available in rural areas, such as battery, diesel generator, pedal generator, pico hydro, photovoltaic (PV) solar home system, and wind. Preference for one of the options depends on energy-source availability, economic feasibility, rural economic development, disposal of residues, nature of end-user application, and government programs and policies. Pico hydro is the preferred electricity generation source in most rural households, followed by wind, PV, and diesel generators. This paper concurs that households in rural areas will be able to afford for electricity access if the payment schedule of the electrification cost is extended and interest rates and taxes, if any, are dropped.