Greater Mass Flow Rate Research Articles

Analysis of Cascade Vapour Refrigeration System with Various Refrigerants

Abstract In this paper report the performance analysis of different refrigerants couples in cascade refrigeration system. Refrigerants such as R134a/R23, R410A/R23 and R404A/R170 have been successfully analyzed in the superheating and sub cooling range of 10 °C and 5 °C respectively. The variation in condenser temperature was from 30 to 50 °C in high temperature circuit while evaporator temperature in low temperature circuit varied in the range of -70°C to -50 °C. The compressor efficiency was assumed to be 0.7 throughout the experiment. It has been revealed that there is enhancement in coefficient of performance and flow rate with rise in compressor work and evaporator temperature. From the present study we conclude that the refrigerant pair R134a/R170 was found to have greater coefficient of performance and lower mass flow rate and the pair R404A/R508B was found to have smaller coefficient of performance and greater mass flow rate.

Energy and exergy analyses of a solar air heater with wire mesh-covered absorber plate

Thermodynamic analysis on a novel design of solar air heater (SAH) having absorber plate covered with copper wire mesh was presented in this study. The newly-designed collector was tested for various air flow rates and tilt angles of the collector. The study was carried out for mass flow rates of 0.030 kg/s and 0.055 kg/s as well as collector tilt angles of 25° and 35°. Thermal efficiency, thermo-hydraulic efficiency and exergetic efficiency were computed by using experimental data. The results indicated that temperature at the outlet of collector, useful heat amount and pressure loss through collector were increased for higher mass flow rate and smaller collector tilt angle. Thermal efficiency of collectors was in the range of 34-82%, thermo-hydraulic efficiency was 25-66% and exergetic efficiency was 3.70-9.65% depending on the studied case. It may be suggested that greater mass flow rate and the lower tilt angle can lead to remarkable improvements in thermal and exergetic efficiencies of SAH with wire mesh on its absorber plate.

Performance of different process additives on the properties of mango powder obtained by drum drying

ABSTRACTThe use of process additives was evaluated in the drum drying of commercial mango pulp, using corn starch, maltodextrin 10/20 DE, and glyceryl monostearate (GMS). The mass flow rate (MFR) and some powder properties were analyzed: moisture content, vitamin C, total phenolic compounds, carotenoids, β-carotene, glass transition temperature (Tg), hygroscopicity, solubility, color, rheological behavior and color of reconstituted pulp. The pulps presented non-Newtonian and pseudoplastic fluid behavior, while Tg values ranged from 29°C to 38°C. The process performed with 3% corn starch and 0.5% GMS (dry basis) resulted in greater MFR (8.0 ± 0.2 kg/h m2) and vitamin C retention (61.0 ± 0.7%).

Analyze of laminar flow and boiling heat transfer characteristics of R134a in the horizontal micro-channel under low temperature condition

A numerical investigation has been carried out to examine the characteristics of laminar flow and boiling heat transfer of R134a in horizontal micro-channel with hydraulic diameter of 1mm. Three-dimensional equations considering conjugate heat transfer, viscous heating and temperature-dependent properties are solved for the fluid flow and heat transfer by ANSYS FLUENT. The influence of refrigerant mass velocity, heat flux density and gasification rate on boiling heat transfer was studied. Results show that under the low temperature condition, the total pressure drop increase with the heat flux along the tube, which caused the saturation temperature of refrigerant decrease, and evaporate strengthen, therefore, the total temperature increase at first and then slow down, the heat flux is mainly used in phase-change in this stage. It also can be found that the greater mass flow rate is more advantageous to evaporation.

Crystallization of Spherical Common Salt in the Submillimeter Size Range without Habit Modifier

Nearly spherical morphology of solution-grown NaCl particles in the size range of 300−1000 μm was achieved at 55−60 °C employing a suitable crystallizer equipped with a butterfly wing-shaped impeller operated at 250 rpm. Morphology control was equally effective with synthetic and natural brines and required no habit modifier. Sieved spherical salt of 350−500 μm size exhibited superior flow (ca. 20% greater mass flow rate through a funnel; angle of repose ∼16°)—as compared to commercial vacuum evaporated free flow cubic salt of comparable dimension—upon treatment with potassium ferrocyanide anticaking additive. The superior flow characteristic was retained even after 3 months of storage. Scanning electron microscopic studies revealed that the round polycrystalline particles were derived from the stacking of minute NaCl cubes and the average size of the spheres was amenable to reduction through use of ethanol as antisolvent. The process was successfully scaled up to 10 kg level.

Optimisation of Flow Through a Pneumatic Control Valve using CFD Analysis and Experimental Validation

Computational Fluid Dynamics (CFD) is becoming a tool that can be used by engineers to optimise valve performance. CFD is used here to model the fluid flow characteristics through a control valve. By changing various aspects of the internal flow path, the performance of a valve is improved through a greater mass flow rate to optimise its performance. These changes included rounding sharp edges, removing areas of dead-space and moving some internal parts to reduce sharp changes in direction. The CFD model was used to create a new modified design which was then manufactured for testing. The test results were compared to the CFD results from the new model. The CFD and experimental results showed a similar increase in flow rate from the original to the modified valve showing that changes to the internal flow path had a positive effect on the measured flow rate.

A Theoretical Comparison of Heat Transfer into Porous Media by the Injection of Steam or Hot Water

Summary A comparison of the heat-carrying capacity of hot water and steam indicatesthat hot water can impart considerably more heat to a formation than does steamat relatively low pressures. This results from the greater density of hot waterand its corresponding greater mass flow rate at a given injection pressure. Athigher pressures, this advantage of hot water becomes smaller, and itdisappears completely at the critical pressure of water. The relative heat-carrying capacities of hot water and steam are influencedby the presence of residual oil in the formation. Greater oil saturations leadto lower heat-carrying capacities of hot water relative to steam. Thesedifferences are a reflection of differences in relative permeabilities of theflowing fluids. The work reported here is considered to be preliminary in nature; severalbasic simplifying assumptions were used in it. Under conditions other thanthose assumed, the relative effectiveness of hot water and steam could besomewhat different from that reported here. Introduction When heat is imparted to a formation by hot water or steam injection, theoil recovery is increased due to thermal expansion of oil, reduction in oilviscosity and, in the case of steam drive, steam distillation of the crude (1).The degree to which oil recovery is increased is affected particularlyby the temperature dependence of the oil viscosity. In many cases, thereservoir oil viscosity can be reduced several hundred-fold by hot water orsteam heating to drastically increase the oil mobility. Figures 1 and2 show the relationship between temperature and viscosity for steam andwater (2). Note that water viscosity decreases with increasing temperature, butthat the steam viscosity increases with increasing temperature at pressuresbelow 1000 psi. When a reservoir has been selected for heal treatment, it is necessary todetermine the most economical means of transferring heat into it. At firstglance, steam may seem to be a better heat carrier than hot water because itsheat content per unit mass is higher than that of water at the sametemperature.