In Pakistan, the utilization of renewable energy sources is increasing in order to reduce the electricity supply and demand gap. However, concentrated solar power (CSP) generation has not been considered in the country even though it has gained considerable attention worldwide. This study, as such, investigates the potential, performance, and economic analyses of four CSP technologies for different locations in Pakistan. Initially, an assessment of CSP sites, including solar resource, land, and water availability, was undertaken. Then, performance simulations of CSP technologies for four different locations of Pakistan, namely Quetta, Hyderabad, Multan, and Peshawar, were examined. For all cases, highest energy production was achieved in summers and lowest in winters, and CSP plants with evaporative cooling were found to be efficient compared to air cooling. The results also revealed that the Quetta and Hyderabad regions were promising for CSP development while parabolic tough (PT) and solar power tower (SPT) were the suitable CSP technologies for these regions. Specifically, the SPT plant with air cooling could be a favorable option for energy production in Quetta. Lastly, economic analyses revealed the financial feasibility of CSP plants in Pakistan since the levelized cost of energy is found to be significantly low.Processes 2019, 7, 575 2 of 26 negligible. Specifically, an abundant potential of solar energy is available in the country because of its location in the sunbelt. Solar energy can be utilized in two ways: solar photovoltaics (SPV) and concentrated solar power (CSP) [4]. SPV systems are used to convert sunlight directly into electricity whereas CSP systems (also known as solar thermal systems) are used for concentrating and heating a heat transfer fluid (HTF) for a power cycle. In Pakistan, the installation and development of the SPV system is growing [4]. Quaid-e-Azam solar park (QASP), which is the first ever power station in the country consisting of SPV with a capacity of 1000 MW, is under construction [4]. Out of 1000 MW of QASP, 300 MW has been already added to the national grid. Also, several small to large scale projects consisting of solar photovoltaics are under operation and construction [4]. However, CSP systems have not been utilized in Pakistan.CSP is a promising technology for large scale power production. There are four families of CSP technology including (i) parabolic trough collectors (PTC), (ii) solar power tower (SPT), (iii) linear Fresnel reflects (LFR), and (iv) parabolic dish systems (PDs). There are numerous advantages of CSP, such as renewable, clean, low operating cost, etc. However, one of the issues with CSP is soiling of mirrors, where dirt is accumulated on the mirrors/reflectors. It causes a reduction in the electricity production. The soiling effect can be reduced by proper cleaning/washing of the mirrors [5][6][7]. The commercialization of CSP is increasing. For instance, the CSP global capacity was 400 MW in 2006, which increased to 4800 MW in 2017 [8]. The global l...

Concentrated solar power (CSP) is a leading renewable energy technology, and the parabolic trough (PT) is one of the most used configurations of CSP. In the present study, the performance improvement and energy cost reduction of a 50 MWe PT plant for Abu Dhabi, United Arab Emirates (UAE) is presented. The simulations were carried out using the System Advisor Model software. The analyses of a PT plant with different technologies/parameters are undertaken in the first instance for seven cases. These cases include solar multiple, solar collectors, receivers, heat transfer fluid, cooling system (evaporative and air-cooled), thermal energy storage system (4–12 h), and fossil dispatch mode (0.25 to 1.0). Based on these analysis, the eighth case, which is found to be the best-case scenario in this study, was considered by taking into account the best of preceding case results and was determined to be the most suitable both in terms of performance and cost reduction. It is, therefore, concluded from this study that the utilization of CSP plants with a proper selection of technology could help reduce energy costs and environmental pollution, enhance system performance, and meet energy demands effectively.

This review presents the nucleate/convective boiling performance for a variety of important low global warming potential (LGWP) alternatives to commonly used high-global warming potential (GWP) refrigerants (such as R-134a, R404A, and R-410A, etc.). Efforts are stressed on the assessment of their evaporation pressure drop and heat transfer coefficient (HTC) characteristics. These alternatives include R-1234ze(Z), R-1234ze(E), R-1233zd (E), R-1234ze(E), R-410A, R-1234yf, and R-513A. The authors investigated the thermo-fluid properties within and outside a tube, mini-channel, micro-fin tube, and plate heat exchanger. The investigation of the numerical, experimental, and simulated results revealed that the evaporation pressure drop and HTC characteristics were dependent on a variety of variables. These factors include the working fluid’s thermodynamics and transport properties, the refrigerant’s mass flux, heat flux, saturation temperature, the vapor quality, the conditions and flow patterns, the orientation of the heating surface, and the geometry (shape, size, and surface area smooth/enhanced) of the heating surface. An expanded LGWP refrigerants, surfaces, and conditions database is needed. Mechanistic models may assist. These models can optimize boiling, anticipate heat transfer, and develop high-performance geometries.

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