let g be a graph with p vertices and q edges and a = {0, 1, 2, . . . , [q/2]}. a vertex labeling f : v (g) → a induces an edge labeling f∗ defined by f∗(uv) = f(u) + f(v) for all edges uv. for a ∈ a, let vf (a) be the number of vertices v with f(v) = a. a graph g is said to be vertex equitable if there exists a vertex labeling f such that for all a and b in a, |vf (a) − vf (b)| ≤ 1 and the in...

the examination of available vapor pressure data in the case of the methane, ethane, propane and butane halogenated refrigerants, allowed recommendations of standard equations for this property. in this study, three new models include a general correlation; a substance-dependent correlation and an artificial neural network (ann) approach have been developed to estimate the saturated vapor press...

The effects of compressor speed variation on the heat transfer inside a speed controlled compressor were investigated in this study. Based on the lumped capacitance ntethod, the temperatures of the compressor components, the oil, and the refrigerant gas within the shell were modeled and simulated on a relative scale. A diffenmt heat transfer coefficient correlation was developed to evaluate the...

The application of carbon dioxide as natural refrigerant in commercial refrigeration systems has attracted higher interest in recent years for its promising energy efficiency and ecological sustainability. This paper presented the development of a low side scroll compressor for the bottle cooler application in the trans-critical cycle. Experimental tests were performed in two different temperat...

Abstract—In present paper, the performance of various alternative refrigerants is compared to find the substitute of R22, the widely used hydrochlorofluorocarbon refrigerant in developing countries. These include the environmentally friendly hydrofluorocarbon (HFC) refrigerants such as R134A, R410A, R407C and M20. In the present study, a steady state thermodynamic model (includes both first and...

The novella Coraline follows a young girl as she rescues her parents from an alternate reality. In his short story, author Neil Gaiman covers scarcely one week of Coraline’s life. Still, the descriptions of Coraline’s experiences and thoughts can engage Carl Jung’s psychological theories of personality structure and individuation. In particular, I will analyze how Coraline’s character illustrat...

Provisioners capture items both for delivery and for self-feeding. In doing so, they may travel directly to and from a single location, visit several patches on each excursion from a delivery point, or alternate excursions to different destinations. Prey suitable for self-feeding versus delivery have differing attributes, which means that they are often best sought in different places. Visiting...

Refrigerants that are used in refrigeration systems, cause environmental difficulties such as depletion of ozone layer and greenhouse effect. Thus, we must find substitutes for such refrigerants, in this paper, the effect of refrigerant on the thermodynamics performance of refrigeration cycles are studied. To do this, a refrigerator that has designed for R12, is simulated. Results show that pur...

Refrigerants that are used in refrigeration systems, cause environmental difficulties such as depletion of ozone layer and greenhouse effect. Thus, we must find substitutes for such refrigerants, in this paper, the effect of refrigerant on the thermodynamics performance of refrigeration cycles are studied. To do this, a refrigerator that has designed for R12, is simulated. Results show that pur...

Evaporation of HFC134a inside smooth, horizontal tubes is studied. Te,;ts are made with pure refngerant and with oil-refrigerant mixtures. Heat flux has varied from 2 kW/n? to 10 kW/m . The inner diameter of the tubes are 12 mm. T1.1o evaporators are used, 4 and 10 m long. Oil content is varied from 0 to 2.5 mass percentage (synthetic oil, EXP-0275). Oil free HFC134a is found to have higher hea...