This paper proposes a methodology aiming at determining the most influent working variables and geometrical parameters over pressure drop heat transfer during condensation process of several refrigerant gases using exchangers with pipes mini channels technology. A multi-criteria decision making (MCDM) was used; this MCDM includes mathematical method called SIMUS (Sequential Interactive Modellin...

Mucoviscosity-associated gene A (magA) of Klebsiella pneumoniae contributes to K1 capsular polysaccharide (CPS) biosynthesis. Based on sequence homology and gene alignment, the magA gene has been predicted to encode a Wzy-type CPS polymerase. Sequence alignment with the Wzy_C and RfaL protein families (which catalyze CPS or lipopolysaccharide (LPS) biosynthesis) and topological analysis has sug...

In this paper, a first- and second-law analysis of vapor compression refrigeration is presented to estimate propose the replacement R134 with working fluids having less global warming potential (GWP) exergy destruction irreversibilities. Six different refrigerants were studied, namely, R717, R1234yf, R290, R134a, R600a, R152a. A thermodynamic model was designed on Engineering Equation Solver (E...

In this study, two different industrial refrigerators were designed, manufactured and tested to analyze the impact of types fans (Type 1 Type 2) used in cooling systems on performance system. order test fan airflow effects, axial configurations with structures motor technology (EC shaded-pole induction) separate refrigerator rooms accordance TS EN ISO 23953-2 standards. R290 (Propane) was as a ...

Abstract With global warming and climate change, the world is experiencing a steady temperature rise. Hence need for effective efficient air conditioning, cooling refrigeration systems higher than ever. One of key elements influencing system performance working fluid. From 2022, new in UK must not use fluids with potential (GWP) above 150. Widely used R134a, GWP 1430, therefore being banned sui...

air conditioning refrigerant r134a has value of global warming potential (gwp) 1300, which is much higher than mac directive (gwp below 150) passed in july 2006. this prompted a search for alternative refrigerant with gwp value less than 150. r1234yf is a new refrigerant which has lower gwp value of 4. effect of blower speed has been compared and flammability issue of r1234yf has been addressed...

h = heat transfer coefficient q = heat flux from the wall of evaporator to refrigerant Tw =Temperature at the wall of evaporator Tf = Temperature of the refrigerant kal = Conductivity of aluminum t = Thickness of evaporator M& = Mass flow rate of refrigerant Cp = Constant-pressure specific heat of refrigerant Tsat = Saturation temperature of refrigerant Tin = Temperature of refrigerant at inlet...

This paper presents the experimental research into the evaluation of lubricity for polyolester (POE) lubricant with HFC-134a refrigerant in rotary and reciprocating compressors for household refrigerators. In order to evaluate the lubricity for POE lubricant with HFC-134a refrigerant, we conducted 4-balls wear tests in the mixing environment of POE lubricant and HFC-134a refrigerant. In the pre...

A household refrigerator designed to work with R-134a was used as an investigation unit to assess the prospect of using mixed refrigerants. The recital of the refrigerator using mixed refrigerant was investigated and compared with the performance of refrigerator when R-134a was used as refrigerant. The effect of condenser temperature and evaporator temperature on COP, refrigerating effect was i...

A heat pump system requires proper refrigerant charge amount. Once refrigerant is charged into a heat pump system, its charge amount is fixed. For this reason, prediction of optimal refrigerant charge amount is very important in order to yield best performance. Too low charge amount degrades capacity of heat pump. On the other hand, excessive charge amount decreases coefficient of performance (...