this research was conducted at the shahrood agricultural research center in 1382 and 1383 to study the effect of alternate furrow irrigation on potato yield and its economic evaluation. the experimental design was a randomize complete block design and the treatments were: every furrow irrigation (efi), fixed alternate furrow irrigation (fafi), variable alternate furrow irrigation (vafi), fixed ...

The transition from CFC-12 (GWP=10,900) to HFC-134a (GWP=1,430) in the 1990’s in new vehicle air conditioners eliminated the contribution to ozone depletion potential (ODP) from new vehicles and reduced the direct Global Warming Potential (GWP) by over 80%. One proposed alternative is HFC-1234yf (GWP=4). Despite the phase-in success of HFC-134a as a zero ODP automotive refrigerant it is still a...

Refrigerant mixtures seem the most promising candidates as replacement fluids in refrigeration devices and heat pumps. In this paper two prediction methods are proposed for th~ evaluation of the thermal conductivity of refrigerant mixtures in their saturated liquid state and in the subcooled region. The first method is based on the use of mixing rules applied to pure refrigerant data evaluated ...

This paper describes the development of a computer simulation model of an integrated supermarket refrigeration and heating system using natural refrigerants (namely ammonia and hydrocarbons). Initial resultS of the model's performance are presented, showing the influence of some of the operating parameters on system thermal efficiency. This will be validated using data collected from monitoring...

The high speed steel is used as a cutting tool, since it has good quality and reliability at cheaper rate when compared to other cutting tools. So it is very important to increase the ability of the tool further for its reliability. So the best way is to increase the hardness. We have brainstormed to find out alternate tool materials. One novel method namely dipping the ordinary tool bit in a c...

R-502 has been the primary refrigerant for low temperature commercial refrigeration applications for many years. The impending phase-out of CFCs dictates its elimination in the very near future. The identification of alternative(s) for R-502 therefore becomes a high priority. This paper addresses the factors to be evaluated in selecting the best replacement and identifies an azeotropic mixture ...

The microchannels/minichannels are being used in industry to yield compact geometry for heat transfer in a wide variety of application. The channels provide high heat transfer coefficients and the large surface area to volume ratios, has led to their use in compact condensers for air-conditioning and refrigerant systems. In order to achieve the compactness the present work attempts to develop a...

Herein, the application of Carnahan-Starling-vdW-β equation of state (EoS) for 13 refrigerant fluids was investigated. The EoS could predict the saturated liquid densities of these refrigerants over the temperature range of 100-400 K and pressures from zero up to187 MPa with the average absolute deviations of 2.66%. The accuracy of Carnahan-Starling-vdW-β EoS in liquid density prediction was al...