Hydrocarbons as Alternative Refrigerants in Domestic Refrigerators.

Abstract

All Hydrocarbons are compatible with Copper with an exception of Propyne and Propadiene, These hydrocarbons are highly reactive with Copper creating extremely explosive metal acetylides [24]. Hence Propyne and Propadiene require sufficient change in the material of construction of the refrigerator. All hydrocarbons are miscible with conventional mineral lubricant and have outstanding lubrication possessions. Another motivating advantage for these class of refrigerants is positive evaporator pressure with mild corrosion resulting in fewer joint replacements. As we know, negative evaporator pressure admits atmospheric air inside the evaporator causing severe corrosion on mixing with the refrigerants forming strong acids. Studies by Gursaran.D, Mathur and D. S. Jung [25] on heat transfer characteristics of alternate refrigerants indicate that coefficient of heat transfer for Hydrocarbons are meaningfully higher than R12 and R134a both in liquid and gaseous phase. Hence, Hydrocarbons are viable candidates from view point of heat transfer MODELLING OF THERMODYNAMIC PROPERTIES The thermodynamic possessions of refrigerants are required to calculate system performance. The basic properties of hydrocarbons were reported by Salvi-Naokhede [4] et al. Table 1 provides the values of property data at design conditions, viz., pressure ratio, NBP of refrigerants, specific volume of suction vapour and latent heat of vaporization at evaporator pressure, and specific heat ratio for R12 and for alternate refrigerants. The thermodynamic properties required for simulation are modeled using S-R-K equality of state. The roots of the algebraic equivalence for explicit capacity in fluid and gasiform stages are resolved using Cardon's technique. Thermodynamic belongings such as fluid enthalpy vapour enthalpy, fluid entropy, vapour entropy are premeditated over a collection of temperatures utilizing heat and entropy parting functions using the procedure given in Appendix. The reference state is chosen in such a way that the saturated values of enthalpy and entropy are 200 kJ/kg and 1kJ/kgK respectively at 0 o C. A C-program was developed using the procedure given in Appendix to acquire thermodynamic variable indicating their properties at some hotness T. The contributions to the program are NBP, acute temperature, acute stress, molecular mass and wagner coefficients. The saturated and superheated properties are exhibited in isolated output files over the kind mentioned by the customer. The vapor pressure data (Wagner coefficients) and Naught stress explicit heat data for the refrigerants are taken from reference[26].The developed Thermodynamic properties are authenticated for R12 and are in decent covenant with ASHRAE[27] values with acceptable inaccuracy. These developed possessions are then used in the assessment of cycle enactment of the method.