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The objective of this paper is the investigation of the annual performance of a solar power plant with linear Fresnel reflectors in the El-Oued region at Algeria. The solar collectors produce water steam that feeds a turbine to produce electricity. The System Advisor Model (SAM) tool is used for simulation. The mean net daily electricity production rate from 8:30 am to 5:30 pm is 48 MWe, and the respective annual production is 210,336 MWh/year. The mean daily optical efficiency of the solar field was close to 52%, while the mean thermal efficiency was about 39%. The net daily cycle efficiency is found to be 24%. The net capital cost of the examined system is $393 million, and the developer net present value is $47 million; the investor net present value is $15 million, the entire period of capital recovery is 11 years, and the levelized cost of electricity is 0.0382 $/kWh. The solar power plant leads to the yearly avoidance of 420,672 tons carbon dioxide emissions (operational cost savings of $6.1 million). Based on the obtained results, linear Fresnel reflectors can be used to achieve satisfying, energetic, financial, and environmental performance that can lead to sustainability. [ABSTRACT FROM AUTHOR]

The objective of the present work is the investigation of a novel polygeneration system for power, refrigeration and heating production at two temperature levels. The present system uses CO2 as the working fluid, which is an environmentally friendly fluid. The total configuration is a combination of a transcritical refrigeration cycle coupled to a Brayton cycle with recompression, which is fed by a biomass boiler. The examined system, at nominal operating conditions, produces refrigeration at 5 °C, and heating at 45 °C and 80 °C. Additionally, the system can be converted into a trigeneration system where the two heating outputs are produced at the same temperature level. The system was studied parametrically by changing the following seven critical parameters: turbine inlet temperature, high pressure, medium pressure, heat exchanger effectiveness, refrigeration temperature, heat rejection temperature and high heating temperature. In nominal operating conditions, the system energy and exergy efficiencies were 78.07% and 26.29%, respectively. For a heat input of 100 kW, the net power production was 24.50 kW, the refrigeration production was 30.73 kW, while the low and high heating production was 9.24 kW and 13.60 kW, respectively. The analysis was conducted with a developed model in Engineering Equation Solver. [ABSTRACT FROM AUTHOR]

An experimental and numerical investigation of a small linear Fresnel for water heating application has been carried out in Blida, Algeria. The numerical simulation with a 1D modeling in transient mode was performed by using the finite difference method. The thermal evaluation is based on the energy assessments characterized by the differential equations of pure water with a flow mass rate equal to 0.015 kg s−1 and copper absorber tube temperature. Moreover, the Fluent code has been developed in order to conduct the CFD modeling at the absorber tube of the solar collector. SolTrace software has been used to determine the optical behavior of the linear reflector. The average optical efficiency of the device is about 42.97%, but the average value of the experimental thermal efficiency reached 29.21% for 22/01/2015 and 29.20% for 19/02/2015. The average value of pure water temperature for 22/01/2015 is 67.28 °C, while its value for 19/02/2015 is 70.99 °C. This solar experimental setup will reduce the consumption of liquefied natural gas by 88.9 m3, which will reduce the CO2 emission by 187.93 kg. In addition, its manufacturing cost will be recovered 16 years from the date of use of this heater. [ABSTRACT FROM AUTHOR]

Summary: The objective of this work is the investigation of an alternative refrigeration system, which combines a supermarket CO2 booster system with an organic Rankine cycle. The waste heat after the high‐pressure compressor is used in order to feed the organic Rankine cycle for electricity production. The working fluid in the organic Rankine cycle is selected to be the octamethyltrisiloxane (MDM), which has a low global warming potential, and so all the used working fluids in the system are environmentally friendly. The system is studied in the transcritical region for ambient temperatures from 27°C to 40°C. In every case, the system is optimized in order to minimize the overall electricity demand. According to the final results, the system coefficient of performance (COP) can be enhanced from 4.83% to 7.60%, while the electricity consumption can be reduced from 4.60% to 7.03% compared with the conventional booster system. Higher enhancements are found in cases with higher ambient temperatures. Furthermore, a preliminary financial study indicates that the examined idea is viable with the simple payback period to be 5.45 years. The present study is conducted by using a homemade model written in Engineering Equation Solver. The objective of this work is the investigation of an alternative refrigeration system, which combines a supermarket CO2 booster system with an organic Rankine cycle. According to the final results, the system coefficient of performance (COP) can be enhanced from 4.83% to 7.60%, while the electricity consumption can be reduced from 4.60% to 7.03% compared with the conventional booster system. Furthermore, a preliminary financial study indicates that the examined idea is viable with the simple payback period to be 5.45 years. [ABSTRACT FROM AUTHOR]

Background Neisseria meningitidis (Nm) is a nasopharyngeal commensal carried by healthy individuals. However, invasive infections occurs in a minority of individuals, with devastating consequences. There is evidence that common polymorphisms are associated with invasive meningococcal disease (IMD), but the contributions of rare variants other than those in the complement system have not been determined. Methods We identified familial cases of IMD in the UK meningococcal disease study and the European Union Life-Threatening Infectious Disease Study. Candidate genetic variants were identified by whole-exome sequencing of 2 patients with familial IMD. Candidate variants were further validated by in vitro assays. Results Exomes of 2 siblings with IMD identified a novel heterozygous missense mutation in BPIFA1 / SPLUNC1. Sequencing of 186 other nonfamilial cases identified another unrelated IMD patient with the same mutation. SPLUNC1 is an innate immune defense protein expressed in the nasopharyngeal epithelia; however, its role in invasive infections is unknown. In vitro assays demonstrated that recombinant SPLUNC1 protein inhibits biofilm formation by Nm, and impedes Nm adhesion and invasion of human airway cells. The dominant negative mutant recombinant SPLUNC1 (p.G22E) showed reduced antibiofilm activity, increased meningococcal adhesion, and increased invasion of cells, compared with wild-type SPLUNC1. Conclusions A mutation in SPLUNC1 affecting mucosal attachment, biofilm formation, and invasion of mucosal epithelial cells is a new genetic cause of meningococcal disease. [ABSTRACT FROM AUTHOR]

The solar collector (reflector and receiver) is the primary device being used in the concentrating solar power technologies for tapping the solar energy to meet various objectives. The performance of the solar collector is influenced by the type of reflector and receiver being selected, and its material also has significant impact. The choice of the heat transferring medium, storage material, receiver design and its performance parameter also influences the solar collector's performance. In this regard, a review has been carried out for these parameters and presented in this paper to highlight the challenges encountered, new methodologies identified and proposed, and future research needs by various researchers to improvise the thermal efficiencies of the different types of collectors used in the concentrating solar power technologies. [ABSTRACT FROM AUTHOR]

• The use of an absorption chiller for subcooling in a CO 2 system is studied. • The absorption chiller is fed by waste heat after the compressor. • In all the cases, the examined system is more efficient than the reference. • The mean COP enhancement is about 23% while the maximum is 75%. • The enhancements are greater in the cases with higher compressor pressure ratio. The objective of this work is to examine a transcritical CO 2 refrigeration system coupled to a single-effect absorption chiller. The role of the absorption machine is to create a subcooling after the gas-cooler in order to increase the COP. The absorption system is fed by waste heat after the CO 2 compressor and so there is not any need for any external energy source. The analysis is conducted with a validated numerical model which is developed in Engineering Equation Solver. The system is studied and optimized for different heat rejection temperatures from 35°C up to 50°C and for different refrigeration temperatures from -35°C up to 5°C. It is found that there is COP enhancement in all the operating scenarios and especially in the cases with higher heat-rejection temperature and lower refrigeration temperature. The mean COP enhancement is about 23.4% which is an important enhancement for designing more efficient systems. [ABSTRACT FROM AUTHOR]

The cutting fluid is significant in any metal cutting operation, for cooling the cutting tool and the surface of the workpiece, by lubricating the tool-workpiece interface and removing chips from the cutting zone. Recently, many researchers have been focusing on minimum quantity lubrication (MQL) among the numerous methods existing on the application of the coolant as it reduces the usage of coolant by spurting a mixture of compressed air and cutting fluid in an improved way instead of flood cooling. The MQL method has been demonstrated to be appropriate as it fulfills the necessities of 'green' machining. In the current study, firstly, various lubrication methods were introduced which are used in machining processes, and then, basic machining processes used in manufacturing industries such as grinding, milling, turning, and drilling have been discussed. The comprehensive review of various nanofluids (NFs) used as lubricants by different researchers for machining process is presented. Furthermore, some cases of utilizing NFs in machining operations have been reported briefly in a table. Based on the studies, it can be concluded that utilizing NFs as coolant and lubricant lead to lower tool temperature, tool wear, higher surface quality, and less environmental dangers. However, the high cost of nanoparticles, need for devices, clustering, and sediment are still challenges for the NF applications in metalworking operations. At last, the article identifies the opportunities for using NFs as lubricants in the future. It should be stated that this work offers a clear guideline for utilizing MQL and MQL-nanofluid approaches in machining processes. This guideline shows the physical, tribological, and heat transfer mechanisms associated with employing such cooling/lubrication approaches and their effects on different machining quality characteristics such as tool wear, surface integrity, and cutting forces. [ABSTRACT FROM AUTHOR]