The effect and contribution of wind generated rotation on outlet temperature and heat gain of LS-2 parabolic trough solar collector

The Monte Carlo ray tracing method is applied and coupled with finite volume numerical methods to study effect of rotation on outlet temperature and heat gain of LS-2 parabolic trough concentrator (PTC). Based on effect of sunshape, curve of mirror and use of MCRT, heat flux distribution around of inner wall of evacuated tube is calculated. After calculation of heat flux, the geometry of LS-2 Luz collector is created and finite volume method is applied to simulate. The obtained results are compared with Dudley et al test results for irrotational cases to validate these numerical solving models. Consider that, for rotational models ,the solving method separately with K.S. Ball's results. In this work, according to the structure of mentioned collector, we use plug as a flow restriction. In the rotational case studies, the inner wall rotates with different angular speeds. We compare results of rotational collector with irrotational. Also for these two main states, the location of plug changed then outlet temperature and heat gain of collector are studied. The results show that rotation have positive role on heat transfer processing and the rotational plug in bottom half of tube have better effectual than upper half of tube. Also the contribution of rotation is calculated in the all of case studies. Working fluid of these study is one of the oil derivatives namely Syltherm-800. The power of wind can be used to rotate tube of collector

Energic, Exergic, Exergo‐economic investigation and optimization of auxiliary cooling system (ACS) equipped with compression refrigerating system (CRS)

Heller main cooling tower as air-cooled heat exchanger is used in the combined cycle power plants (CCPP) to reduce the temperature of condenser. In extreme summer heat, the efficiency of the cooling tower is reduced and it lessens performance of Steam Turbine Generation (STG) unit of Combined Cycle Power Plant (CCPP). Thus, the auxiliary cooling system (ACS) is equipped with compression refrigerating system (CRS). This auxiliary system is linked with the Heller main cooling tower and improves the performance of power plant. In other words, this auxiliary system increases the generated power of STG unit of CCPP by decreasing the temperature of returning water from cooling tower Therefore, in the first step, the mentioned auxiliary cooling system (ACS) as a heat exchanger and compression refrigerating system (CRS) have been designed via ASPEN HTFS and EES code respectively. In order to validate their results, these two systems have been built and theirs experimentally obtained data have been compared with ASPEN and EES results. There are good agreements between results. After that, exergic and exergo-economic analysis of designed systems have been carried out. Finally, the compression refrigerating system (CRS) has been optimized via Genetic Algorithm (GA). Increasing in exergy efficiency (ε) from 14.23% up to 36.12% and decreasing the total cost rate (ĊSystem) from 378.2 ($/h) to 308.2 ($/h) are as results of multi-objective optimization

A comparative study on energy inputs and yield of canola production under different environmental conditions

Zeynab Ramedani, Mahmoud Omid, Faezeh Fahimi and Farzad Mirzaee (2012) A comparative study on energy inputs and yield of canola production under different environmental conditions. Journal of Agricultural Technology 8(3): 811-824. The energy consumption and sensitivity analysis for inputs for canola production in Iran for two climateorological conditions (Qom city with dry climate and Kordkuy city with humid climate) were determined. Data were collected from 30 and 35 producers in Qom and Kordkuy cites by using face to face questionnaire method. The results indicated that total energy consumed in Qom and Kordkuy were 111926.53 MJ/ ha and 27059.89 MJ/ ha, respectively. The net energy of canola production for Qom city was -28810 MJ/ ha while this value for Kordkuy was 44538.51 MJ/ ha. The energy ratios were 0.74 and 2.65 and the ratio of direct to indirect energy forms were 90:10 and 70:30 in Qom and Kordkuy, respectively. The evaluation of econometric model showed that the impact of seed and diesel fuel were significant at level of 1%, for both two climateorological conditions. The sensitivity analysis indicated that with increasing energy of 1 MJ in seed or diesel fuel yield increased by ratio of 13.45 and 31.35 in Qom and Kordkuy, respectively

Dry Sliding Wear and Corrosion Performance of Mg-Sn-Ti Alloys Produced by Casting and Extrusion

The aim of the present study is to investigate the role of Ti on corrosion and the wear properties of Mg-5Sn-xTi (x = 0, 0.15, 0.75, 1.5 wt.%) alloys. The samples were fabricated by conventional casting followed by hot extrusion, and the studies were examined by means of a pin-on-disc tribometer at various loads of 6, 10, and 20 N with constant sliding velocities of 0.04 m/s at ambient temperature. The corrosion performance, using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), was studied in a basic solution containing 3.5 wt.% NaCl. The observation indicated a drop in the wear rate with an increase in Ti, while the average coefficient of friction was raised in higher Ti contents compared to the base material. The sample with 0.75 wt.% Ti exhibited superior wear properties at 6 and 10 N of normal force, while the sample with 0.15 wt.% Ti presented better wear resistance for 20 N. Electrochemical test observations demonstrated that the Ti deteriorated the corrosion features of the Mg-5Sn alloy, owing to the galvanic effects of Ti. The Mg-5Sn alloy exhibited excellent corrosion behavior (corrosion potential (Ecorr) = −1.45V and current density (Icorr) = 43.92 A/cm2). The results indicated the significant role of Ti content in modulating wear and corrosion resistance of the Mg-5Sn alloy