Thermodynamic Analysis of R152a and Dimethylether Refrigerant Mixtures in Refrigeration System

Abstract R-134a is currently used as the refrigerant in refrigerator replacing the ozone depleting refrigerant R-12. Although R134a has no Ozone Depletion Potential (ODP), it has a relatively larger Global Warming Potential (GWP) of 1300. In an effort to reduce greenhouse gas emissions, R-152a (difluoroethane) (GWP 130) and Hydrocarbons (GWP 20) are being considered as a replacement for R-134a. HC blend has a zero ODP and a negligible GWP. The only drawback of HC blend is the temperature glide. The drawbacks of using R-152a and HC blend with respect to GWP and temperature glide can be overcome by the refrigerant DME. The present paper presents the results of a thermodynamic study of new eco-friendly refrigerant blends of R-152a and DME. It was carried out for a single-stage vapor compression refrigeration system. These new refrigerants are generally azeotropic. Some of these new mixtures have better thermodynamic properties than those of pure R-152a. RefProp software has been used to determine the thermodynamic properties of the refrigerant blends. In this analysis, experimental validation of the new refrigerant mixture (60% DME + 40% R-152a) is carried out in domestic refrigerator. The results are better than those of R-152a and R-134a

Development of mathematical model to predict the mechanical properties of friction stir

This paper presents a systematic approach to develop the mathematical model for predicting the ultimate tensile strength,yield strength, and percentage of elongation of AA6351 aluminum alloy which is widely used in automotive, aircraft anddefense Industries by incorporating (FSW) friction stir welding process parameter such as tool rotational speed, weldingspeed, and axial force. FSW has been carried out based on three factors five level central composite rotatable design withfull replications technique. Response surface methodology (RSM) is employed to develop the mathematical model. Analysisof variance (ANOVA) Technique is used to check the adequacy of the developed mathematical model. The developedmathematical model can be used effectively at 95% confidence level. The effect of FSW process parameter on mechanicalproperties of AA6351 aluminum alloy has been analyzed in detail

Experimental investigation on Zirconia coated high compression spark ignition engine with ethanol as fuel

789-794This study presents effect of coating on piston, cylinder head, and valves on the performance of a modified four stroke diesel engine using wet ethanol (5% water) as a fuel and emission characteristics of exhaust gas. Zirconia, which has low thermal conductivity, high temperature resistance, chemical inertness, high resistance to erosion, corrosion and high strength, was selected as a coating material for engine components. Ethanol was sprayed in inlet manifold and spark plug was erected on engine head to facilitate ignition. Engine’s performance was studied for both wet ethanol and diesel with and without Zirconia coating. Also, emissions values were recorded to study the engine’s behavior on emissions

Acromegaly in pregnancy

Pregnancy in a patient with acromegaly is a rare occurrence. Here in, we report a patient with acromegaly who presented to us in the 2 nd trimester of pregnancy with visual loss in the right eye. Her vision improved after surgery. She went on to have an uneventful pregnancy and delivered a term baby, by caesarian section. One year following her delivery, she received stereotactic radiotherapy. Subsequent follow-up revealed that her tumor had regressed and her IGF-1 levels had normalized

Three siblings with Woodhouse–Sakati syndrome in an Indian family

Woodhouse–Sakati syndrome consists of alopecia, hypogonadism, diabetes mellitus, mild mental retardation, sensorineural deafness and ECG abnormalities. The proband described here has the above-mentioned features and presented with idiopathic thrombocytopenic purpura not reported before. Phenotypic variability is present in the three affected siblings. The two sisters have hypergonadotropic hypogonadism and the brother has hypogonadotropic hypogonadism. Camptodactyly of fourth and fifth fingers is seen in proband and her brother. We report for the first time three affected siblings of Woodhouse–Sakati syndrome in an Indian family