Theoretical Study of a Novel Multi Vane Rotary Compressor
Abstract
This paper presents results of a theoretical study on a new novel concept of a multi-vane rotary (MVR) compressor with the axis vertical. In this concept a sleeve (or cylinder) and a mechanical rotor are eccentrically mounted such that both touch each other circumferentially at one linear point of contact during a rotation. One vane (primary) has its rounded end embedded fairly loosely into the sleeve causing it to be rotated along with the vane and at the same time the vane reciprocates in a slot in the mechanical rotor. The other vanes (secondary) are free to slide out of their respective slots in the rotor, by centrifugal force and are similarly pushed in by the rotating sleeve. With this arrangement compression is guaranteed at all speeds. As soon as the rotor begins to rotate suction and compression chambers are respectively created by the primary vane, while the secondary vanes only start performing the compression function when enough centrifugal force has been built up. In addition, the relative rotation between the sleeve and each secondary vane reduces rubbing between the two. With this arrangement the study found out that the performance of the compressor is significantly improved compared to other similar existing refrigerant compressors of multi-vane rotary type. The reduction in friction is estimated to be about 45%. Analysis of instantaneous internal leakage was also conducted and was found that this new compressor concept possesses a relatively high volumetric efficiency. The work is currently continued involving designing, fabricating and performance testing of the compressor.geometry (number of transfer units), the thermal-hydraulic characteristics (friction factor and Colburn j-factor), and the operating conditions (heat transfer duty, core velocity, coil surface temperature, and fluid properties) is derived. It is shown that for heat exchanger with constant wall temperature (i.e., condensers and evaporators), there does exist a particular number of transfer units which minimizes the dimensionless rate of entropy generation. An algebraic expression for the optimum heat exchanger effectiveness, based on the working conditions, heat exchanger geometry and fluid properties, is also presented. The theoretical analysis led to the conclusion that a high This paper presents results of a theoretical study on a new novel concept of a multi-vane rotary (MVR) compressor with the axis vertical. In this concept a sleeve (or cylinder) and a mechanical rotor are eccentrically mounted such that both touch each other circumferentially at one linear point of contact during a rotation. One vane (primary) has its rounded end embedded fairly loosely into the sleeve causing it to be rotated along with the vane and at the same time the vane reciprocates in a slot in the mechanical rotor. The other vanes (secondary) are free to slide out of their respective slots in the rotor, by centrifugal force and are similarly pushed in by the rotating sleeve. With this arrangement compression is guaranteed at all speeds. As soon as the rotor begins to rotate suction and compression chambers are respectively created by the primary vane, while the secondary vanes only start performing the compression function when enough centrifugal force has been built up. In addition, the relative rotation between the sleeve and each secondary vane reduces rubbing between the two. With this arrangement the study found out that the performance of the compressor is significantly improved compared to other similar existing refrigerant compressors of multi-vane rotary type. The reduction in friction is estimated to be about 45%. Analysis of instantaneous internal leakage was also conducted and was found that this new compressor concept possesses a relatively high volumetric efficiency. The work is currently continued involving designing, fabricating and performance testing of the compressor.