A heat exchanger that arranges flat tubes horizontally has a vertical header that distributes the refrigerant to each tube. When the heat exchanger works as an evaporator, differences in flow conditions at each branch...A heat exchanger that arranges flat tubes horizontally has a vertical header that distributes the refrigerant to each tube. When the heat exchanger works as an evaporator, differences in flow conditions at each branch, such as the ratio and distribution of vapor and liquid, due to the differences in densities and momentums of vapor and liquid in the two-phase flow make equal distribution difficult. This paper describes the distribution characteristics of a four-branch header that has a rectangular cross-section without the internal protrusion of flat tubes in the case of the inflow of the refrigerant R32 from the bottom of the header by using an equipment that can estimate the distribution ratio of the liquid and vapor phase to each branch. This paper also discusses the distribution characteristics on the basis of the flow visualization in the header. The flow visualization shows that a liquid level that contains vapor phase exists in the header and affects the distribution greatly.展开更多
This experimental analysis shows the measured reduction in energy consumption as well as the effects of voltage on cycle temperatures, pressures, flow rates and also compressor speed （revolutions per minute）. The do...This experimental analysis shows the measured reduction in energy consumption as well as the effects of voltage on cycle temperatures, pressures, flow rates and also compressor speed （revolutions per minute）. The domestic refrigerator used R134a as refrigerant. Two energy consumption procedures were adapted from the JIS and ISO standards. The biggest difference between two standards is that the fridge is not opened in the ISO test while it is opened a number of times in the JIS test. The tests were carried out between 190 V and 250 V in steps of 10 V. The reduction in energy consumption was of 49.78 W-h per day or 6.27% of the total consumption. The experiments also showed that the voltage drop resulted in only a small rpm drop which in turn did not result in a noticeable refrigerant flow-rate change. Consequently the temperatures and pressures were not affected.展开更多
文摘A heat exchanger that arranges flat tubes horizontally has a vertical header that distributes the refrigerant to each tube. When the heat exchanger works as an evaporator, differences in flow conditions at each branch, such as the ratio and distribution of vapor and liquid, due to the differences in densities and momentums of vapor and liquid in the two-phase flow make equal distribution difficult. This paper describes the distribution characteristics of a four-branch header that has a rectangular cross-section without the internal protrusion of flat tubes in the case of the inflow of the refrigerant R32 from the bottom of the header by using an equipment that can estimate the distribution ratio of the liquid and vapor phase to each branch. This paper also discusses the distribution characteristics on the basis of the flow visualization in the header. The flow visualization shows that a liquid level that contains vapor phase exists in the header and affects the distribution greatly.
文摘This experimental analysis shows the measured reduction in energy consumption as well as the effects of voltage on cycle temperatures, pressures, flow rates and also compressor speed （revolutions per minute）. The domestic refrigerator used R134a as refrigerant. Two energy consumption procedures were adapted from the JIS and ISO standards. The biggest difference between two standards is that the fridge is not opened in the ISO test while it is opened a number of times in the JIS test. The tests were carried out between 190 V and 250 V in steps of 10 V. The reduction in energy consumption was of 49.78 W-h per day or 6.27% of the total consumption. The experiments also showed that the voltage drop resulted in only a small rpm drop which in turn did not result in a noticeable refrigerant flow-rate change. Consequently the temperatures and pressures were not affected.
