A method of minimizing energy use in a chiller and cooling tower system is disclosed. The method comprises the steps of: determining a measure of chiller efficiency; determining a measure of cooling tower efficiency; determining a measure of the transfer rate of heat energy between the cooling tower and the chiller; calculating a near optimal water temperature as a function of the chiller work efficiency, the cooling tower efficiency and the transfer rate; and operating the cooling tower to provide a conditioned fluid at the temperatures to produce near optimal energy consumption.

Near optimization of cooling tower condenser water

A turbomachinery is presented to provide stable operation at fluid flow rates much lower than the design flow rate without introducing surge in the device. This is achieved by providing a diffuser with variable angle vanes. The vane angle at low flow rates is adjusted so as to minimize the diffuser loss of the exiting fluid stream from the impeller. Since the flow angle of the exit flow of the impeller is a function only of the non-dimensional flow rates, and does not depend on the flow angle at the inlet the impeller, therefore, the vane angles can be regulated to achieve a stable operation of the impeller without producing surge of the turbomachinery at flow rates lower than the design flow rate. To optimize the performance of the turbomachinery, in addition to the variable angle vanes, an inlet guide vane having variable vane angle is provided so that the turbomachinery can be operated at the required flow rate and head pressure. The concept is demonstrated in a turbomachinery provided with variable diffuser vanes and an inlet guide vane.

Turbomachinery with variable angle fluid guiding devices

A system for servicing a computer controlled machine comprising: a computer controlled machine including a device operable to perform a function, a controller controlling the operation of that device, and a data access port for transferring data and commands from the controller; and a service tool operably connected to the data access port, the service tool including a remote communications capability, a computer, and diagnostics and graphing software; and an expert observer system operably linked to the remote communications capability of the service tool and including historical machine data, machine sales information, software revisions for the controller, additional diagnostics software, and an expert observer capable of providing a mentor capability to the operator of a service tool.

HVAC service tool with internet capability

The compressor in a refrigeration system is controlled solely by a variable speed drive which controls the motor of the compressor by virtue of the varying of the frequency of the electricity provided to the motor. To minimize the initial cost and to minimize operating costs, the variable speed drive is cooled by refrigerant from the refrigeration system which permits the use of a smaller drive, and the variable speed drive is operated at, or approaching, a unity power factor.

Variable speed drive chiller system

A centrifugal compressor assembly for compressing refrigerant in a 250-ton capacity or larger chiller system comprising a motor, preferably a compact, high energy density motor or permanent magnet motor, for driving a shaft at a range of sustained operating speeds under the control of a variable speed drive Another embodiment of the centrifugal compressor assembly comprises a mixed flow impeller and a vaneless diffuser sized such that a final stage compressor operates with an optimal specific speed range for targeted combinations of head and capacity, while a non-final stage compressor operates above the optimum specific speed of the final stage compressor Another embodiment of the centrifugal compressor assembly comprises an integrated inlet flow conditioning assembly comprising a flow conditioning nose, a plurality of inlet guide vanes and a flow conditioning body that positions inlet guide vanes to condition flow of refrigerant into an impeller to achieve a target approximately constant angle swirl distribution with minimal guide vane turning

Centrifugal compressor assembly and method

A method of controlling the operation of a centrifugal compressor in a water chiller system. The compressor's capacity is variable by modulating its speed of rotation or by modulating its inlet guide vane's position. The water chiller includes an evaporator having a leaving water temperature. The method comprises the steps of: monitoring the leaving water temperature; determining if the leaving water temperature is in a steady state; modulating the compressor capacity by modulating speed of rotation if the leaving water temperature is in a steady state; and modulating the compressor capacity by modulating inlet guide vane position if the leaving water temperature is not in a steady state.

Control method and apparatus for a centrifugal chiller using a variable speed impeller motor drive

A control system method, for a centrifugal compressor having variable inlet guide vanes and at least one rotationally driven impeller, has a first control mode in which the control of the compressor capacity is a function of vane positioning and impeller speed variations and a second, most efficient, control mode in which the control of the compressor capacity is a function of impeller speed variations with the vanes fixed in the fully open position, the control method moving from the first control mode to the second on sensing the compressor operating in a steady state condition, and moving from the second mode to the first on one or more of: detecting that the compressor is operating outside its operating condition control limit region; detecting that the defined limits compelling that the compressor be unloaded have been exceeded, detecting the occurrence of a surge condition.

Goshaw Craig M

Papers

Control method and apparatus for a centrifugal chiller using a variable speed impeller motor drive

Control system method for a centrifugal compressor

Control of variable capacity centrifugal compressors