Influence of Horizontal Pipe Length to Flooding of Counter Current of Water-Air Flow in Complex Pipe

This research has been conducted study the effect of horizontal pipe length on flooding phenomenon. Observation of the flow phenomenon has used high speed camera. Working fluids for this study were water-air and the water flow was countercurrent to the air through a hot leg simulator. Hot leg simulator consisted of an acrylic horizontal pipe with inside diameter of 25.4 mm and an elbow with inclination angle of 500. The ratio of length to diameter pipe used in this study L/D = 25, L/D = 50 and L/D = 94.5. Water superficial velocity (JL) were 0.016 m/s, 0.049 m/s, 0.082 m/s. For each water superficial velocity, air superficial velocity (JG) was increased gradually with 0.1646 m/s from 0 m/s until flooding phenomenon appeared. Time interval to change air superficial velocity was 15 seconds. The result of this study was flooding phenomenon appeared earlier for higher L/D, and it was observed that the onset of flooding shifted toward the bend. It was also observed that flooding phenomenon shifted away from the bend for higher JL while L/D kept constant

INVESTIGASI EKSPERIMENTAL PERFORMA SISTEM PENDINGIN MULTI-TERMOELEKTRIK DENGAN KONFIGURASI TERMAL SERI DAN PARALEL

Thermoelectrics can convert electrical energy to thermal energy. The generated thermal energy can be used in various cooling systems (TEC) applications. Improvement of TEC performance influenced by hot-side heat dissipation method, working fluid, and multi-thermoelectric. This study aims to investigate the relation between multi-thermoelectric configuration and the cooling behaviors. The experiment was conducted on the devices equipped with two modules of TEC arranged in series and parallel with variations of input voltage, working fluid mass flow, and temperature. The result reveals variations in cooling behaviors between the two configurations. Parallel configuration TEC gives the highest cooling capacity with a value of 66.62 W, 100% bigger than the series configuration. Meanwhile, the series configuration provides a delta temperature of 11.03 K, 2% higher than the parallel one. The parallel modules cooling performance is the biggest among the two arrangement, with a value of 2.57, which is 147% higher than series one

Characteristic Study of Film Thickness on Countercurrent of Water-Air Flow in Hot-Leg Simulator of L/D = 25 by using Parallel-Wire Methods

In water-air counter current flow, relative movement between water and air occurred. The results of this movement interfacial instability occurred in the flow, causing the liquid film moves up and down. In this study, film thickness characteristics of water-air counter current flow in L/D=25 hot-leg simulator are identified. Film thickness measurement was carried out using parallel-wire sensor consists of parallel wires installed through the pipe’s cross sectional area with spacing of 5 mm. sensor has wire diameter of 0,51 mm made from copper coated in silver. This experimental study was carried out with water superficial velocity (JL) variation of JL=0,003 m/s, JL=0,032 m/s, and JL=0,065 m/s. From the film thickness measurement, film thickness characteristics of water-air counter current flow are identified based on the flow pattern and the position of onset of flooding. JL variation affects the occurring time of flow pattern change, hydraulic jump, and onset of flooding. Hydraulic jump and onset of flooding position occurred further from the bend as the JL increased. Onset of flooding occurrence time is faster as the JL bigger

Investigation Of Modified Ejector Cycle On Residential Air Conditioner With Environmentally Benign Refrigerant Of R290

This paper investigates a modified ejector cycle (MEC) to further enhance the COP improvement of residential air conditioner (A/C), as compared to the standard ejector cycle (SEC). This paper also presents numerical and experimental studies of the MEC. Numerical approach of MEC performances was evaluated by using SEC cycle that had been developed by many researchers. In the experimental study of MEC, three motive nozzle diameters of 0.9, 1.0 and 1.1 mm were utilized. In addition, environmentally friendly refrigerant of R290 (propane) was used as a working fluid. The modeling results of residential A/C with the cooling capacity of 2.5 kW showed higher COP improvements of MEC than SEC for all entrainment ratios of the ejector. There was no COP improvement for SEC at a low entrainment ratio, whereas there are always COP improvements for all entrainment ratios for MEC. In addition, the experimental results showed the highest COP improvement of 16.67% was achieved with the motive nozzle diameter of 1.1 m

KAJI EKSPERIMENTAL RETROFIT R404A DENGAN REFRIGERAN RAMAH LINGKUNGAN R290 PADA FREEZER

R404A refrigerant is still widely used as the working fluid in freezers with temperatures below -30°C. However, because of R404A’s high global warming potential (GWP) value, its use as a working fluid should be stopped immediately. One alternative is an environmentally friendly refrigerant, that is R290. In this study, the R404A refrigerant was replaced by R290 in a freezer that can reach -40°C. In the case of replacing a refrigerant with a different type, the reference used is the same charging volume in the system. The filling mass of R290 is the ratio of the density of R404A to R290 at its evaporation temperature, which is -40°C. The amount of R404A’s mass filling is 170 g, while the amount of R290’s mass filling is 62.9 g. Based on a 120-minutes testing, replacing R404A with R290 has resulted in the reduction of power input by 6.0%, as well as in the slight increase of its cooling capacity, which is 2.42%. As a result of the input power decrease and the cooling capacity increase, the COP in the freezer also increased, namely by 8.05%. More importantly, if a leak occurs in the refrigerant, the replacement of R404A with R290 can help reduce gas emissions that contribute to global warming. It is because the GWP value of R404A refrigerant, which is 3922, is replaced by the GWP value of R290 refrigerant, which is only 3