Performance Analysis of a Twin Rotary Compressor
For a twin rotary compressor, a computer simulation program has been developed. With R22, predicted cooling capacity, compressor input and EER were found to be in good agreement with experimental results. Calculated P-V diagram was also compared well to that of measurement. With the simulation program, parametric study has been performed to investigate effects of cylinder dimensions on R410A twin rotary compressor performance. Over the ranges of cylinder dimensions studied, some variations were found for volumetric, adiabatic and mechanical efficiencies, but overall compressor performance did not change much. Discharge port configuration was found to have large effect on adiabatic efficiency, but not much on volumetric efficiency.
Mechanical Loss Analysis Of Inverter Controlled Two Cylinders Type Rotary Compressor
Recently the demanding of 2-3HP inverter controlled air conditioner is growing. Compared with one cylinder type rotary compressor, the torque fluctuation and vibration of the two cylinders type rotary compressor is little, so it is more suitable for large displacement compressor of 2~3HP. In this paper mechanical losses of inverter controlled large displacement two cylinders type rotary compressor is theoretically studied. Based on the dynamic model of moving parts, the computer simulation of the compressor mechanism is carried out. The moving orderliness, the force and lubricating condition of main frictional parts, such as rolling piston, vane, upper and lower bearing, etc, are numerical analyzed. Then the mechanical losses are predicted. The result is compared to that of the corresponding single cylinder type rotary compressor. INTRODUCTION Single rolling piston type rotary compressors are widely used in small capability room air conditionings due to its small size, lightweight, high performance and suitable for volume-producing. The capability of air conditioner is decided on room size and load. Recently the demanding of 2-3HP air conditioner for store or large room is growing. But as for single cylinder rotary compressor, the torque fluctuates much and vibration accelerates along with displacement growing, which still be difficult to put into batch production up to now. Compared with one cylinder type rotary compressor, the torque fluctuation and vibration of the two cylinders type rotary compressor is little, so it is more suitable for large displacement compressor of 2~3HP. (a) single cylinder type rotary compressor (b) two cylinder type rotary compressor Fig. 1 Structure of the compressor As Fig1 shows, a two cylinder rotary compressor includes a closed casing, a compression section, and an electric motorsection, both arranged in the casing, for driving the compression section. The compression section comprises first and second assemblies. The first assembly is constructed by securing a second cylinder to a first bearing, in alignment therewith. The second assembly is constructed by securing a second cylinder to a second bearing, in alignment therewith. The first and second assemblies are aligned with and secured to each other while a partitioning plate is interposed between the first and second cylinders. First and second rollers are rotatably arranged in the first and second cylinders, respectively. These rollers are rotated by a rotational shaft which is supported by the first and second bearings and drived by the electric motor section. Compared to single rolling piston type rotary compressors, the movement of compress mechanical structure is same. But the two cylinder type has two sets of compress mechanism, it will lead to a series of subjects. First, the number of wear parts is increased and the compress force is more complicated than before. Second, the distance between main and sub bearing is longer, which cause heavier and more complicated force acting on crankshaft. So the crankshaft will be easier to deform, several friction problems between main and sub bearing will occur and the mechanical power will increase. In this paper, a theoretical calculation of the compressor mechanical losses is presented based on the compressr moving analysis, force analysis and lubricating analysis. The result is compared to that of the corresponding single cylinder type rotary compressor. THEORETICAL ANALYSIS Movement Analysis Fig.2 shows an analytical model of the movement of one rolling piston in cylinder. As the crankshaft rotates, the rolling piston also rotates around the center of the crankshaft at angular velocity p π . It is assumed that the vane tip is always contact with the outside of the rolling piston, then the vane length in the cylinder is[1]: 2 1 2 2 )] 2 cos 1 ( 2 1 ) [( cos β β − − + − − + = e r R e r R x V r V C Fig 2 Analytical Model Pressure in Compression Chamber The displacement volume of the compression chamber is expressed as th r V V V V V r C V e R R e W W R R R R Rr Rc H Vc e β α β γ γ α α β β π β + + + + + − + − + + − − = ]} cos cos ) )[( sin ( 2 1 cos 4 1 ) ( 2 1 ) ( 2 1 2 1 ) ( { ) ( 2 2 2 2 2 where: ) sin ( sin 1 r V R R e + = − β α , ) 2 ( sin 1 V V R W − = γ Then the pressure in compression chamber is obtained from the following equation. κ β β )] ( / ) 0 ( [ ) ( C C S C V V P P = O Pc R1n R2n R2v
Far-field dispersal modeling for fuel-air-explosive devices
A computer model for simulating the explosive dispersal of a fuel agent in the far-field regime is described and is applied to a wide variety of initial conditions to judge their effect upon the resulting fuel/air cloud. This work was directed toward modeling the dispersal process associated with Fuel-Air-Explosives devices. The far-field dispersal regime is taken to be that time after the initial burster charge detonation in which the shock forces no longer dominate the flow field and initial canister and fuel mass breakup has occurred. The model was applied to a low vapor pressure fuel, a high vapor pressure fuel and a solid fuel. A strong dependence of the final cloud characteristics upon the initial droplet size distribution was demonstrated. The predicted fuel-air clouds were highly non-uniform in concentration. 18 refs., 86 figs., 4 tabs.