Increasing demands for more efficient screw compressors require that compressor designs are tailored upon their duty, capacity and manufacturing capability. A suitable procedure for optimisation of the screw compressor shape, size, dimension and operating parameters is described here, which results in the most appropriate design for a given compressor application and fluid. It is based on a rac...

waterwheels are the oldest types of hydraulic machines. these turbines are of relatively simple design, large diameter, low rotational speed and high torques. but applying them as micro hydros of high speed and small diameter is yet to be explored. a micro hydro waterwheel of one meter diameter was designed and manufactured at the iranian  esearc†h organization for science and technology (irost...

We present a new graph compressor that works by recursively detecting repeated substructures and representing them through grammar rules. We show that for a large number of graphs the compressor obtains smaller representations than other approaches. Specific queries such as reachability between two nodes or regular path queries can be evaluated in linear time (or quadratic times, respectively),...

In small to medium scale buildings located in the subtropics, such as Hong Kong, direct expansion air conditioning (DX A/C) systems are widely applied. This is because, as compared to chilled water based central air conditioning systems, DX A/C systems are compact, flexible for multi-room services, energy efficient and cost less to maintain and operate. However, traditionally, a DX A/C system i...

In this article a low power and low latency 4-2 compressor has been presented. By using modified truth table and Pass Transistor Logic (PTL) a novel structure has been proposed which outperforms previous designs from the frequency of operation view point. The proposed design method has reduced the total transistor count considerably which will lead to reduced power consumption and smaller activ...

A. D. Kelly General Signal Laboratory Equipment 275 Aiken Road Asheville, NC 28806 Low temperature refrigeration mechanically and thermally stresses a compressor's wrist journal bearing. Knowledge of bearing condition would be useful for self-diagnostics or predictive maintenance, particularly in freezers used for storage of valuable biomedical products. This initial investigation considers ext...

Centrifugal compressor and turbine manufacturers are building machines that operate at increasingly higher speeds to reduce the size and cost of their equipment. Helical gears are commonly used to step down the speed of these machines to match nominal motor and generator speeds. The demand for higher compressor and turbine speeds has resulted in an increase in the maximum pitch line velocities ...

Typical automotive air conditioning refrigeration systems employ thermostatic expansion valve or orifice tube controls in a single stage refrigerant circuit. A new automotive air conditioning compressor has been developed that has a two stage compression process, which makes designing and producing a two stage refrigerant circuit more practical. Since this compressor can function in a single st...

This paper presents a new procedure for the speed changing of the twospeed compressor driven by the singlephase Permanent Split Capacitor (PSC) motor. The use of the two-speed motor for compressor is one of the effective ways for their capacity control. But the two speed compressors now in use are driven by three-phase motors. It is because a single-phase, two-speed motor has rather a small sta...