A system, method, and computer-readable medium for determining the flow rate and fluid density in an electrical submersible pump (ESP) and controlling the ESP based on the flow rate and density. In one implementation, an ESP system includes an ESP, drive circuitry, a current sensor, a voltage sensor, and a processor. The ESP includes an electric motor. The drive circuitry is electrically coupled to the ESP and is configured to provide an electrical signal to power the ESP. The current sensor is configured to measure a current of the electrical signal. The voltage sensor is configured to measure a voltage of the electrical signal. The processor is configured to calculate speed of a shaft of the electric motor based on a frequency induced by rotation of the motor detected in the current. The processor is also configured to calculate a density of fluid in the ESP based on the speed.

For a pressure packing with a buffer gas barrier into which a buffer gas is fed via a buffer gas feeding line, a sensing line is provided that is connected at a first end to a vent volume in the pressure packing with an opposite second end of the sensing line being closed, so that there is no gas flow in the sensing line. A pressure regulator is connected to the buffer gas feeding line for setting the buffer gas pressure in the buffer gas feeding line, whereas, during operation of the pressure packing, the pressure in the sensing line is used as pilot pressure for the pressure regulator for setting the buffer gas pressure.

The disclosure discloses a method and a device for controlling cylinder switching of a compressor, a unit and an air conditioning system. The method includes: determining whether the compressor needs to perform cylinder switching; if so, adjusting current operating frequency according to a system pressure difference so that both the adjusted operating frequency and the system pressure difference meet a cylinder switching condition of the compressor; and controlling the compressor to perform cylinder switching. At the moment, the system pressure difference and the operation frequency are stable, and would not interfere the compressor's maintaining of the single-cylinder or double-cylinder operation state, which guarantees the energy efficiency of the unit where the compressor is located, and improves the use experience of a user.

A method, system, and apparatus for testing mobile pumps and mobile fire pumps. Exemplary embodiments described herein can reduce or eliminate the discharge of water used for testing pumps to the ground or other ambient environments. Further, exemplary embodiments can reduce or eliminate the potential for contamination of water bodies and reduce or eliminate need for large transportable reservoirs as a source of water. Exemplary embodiments can include attachment of hose valves to pump outlets for controlling a flow rate of water as well as water pressure. A hose may further be coupled to each hose valve and looped to a pump inlet, allowing for the recycling of water. Flow meters may further be provided on the looped lines to measure water flow. A low flow capacity water source and discharge may be utilized to provide further control of or adjustment to test system temperature, water flow and pressure.

A method for designing a compressor operable to compress a refrigerant. The method may include determining operating conditions for the compressor. The method may also include weighting the operating conditions. The method further include determining a compressor volume ratio based on the refrigerant and the weighted operating conditions.

A method for controlling a compression system that includes a compressor for compressing gas, a first on-off valve provided on a suction flow passage connected to a suction side of the compressor, a pressure reducing valve provided on a portion of the suction flow passage upstream of the first on-off valve, a second on-off valve provided on a discharge flow passage connected to a discharge side of the compressor, a bypass flow passage connecting the suction flow passage and the discharge flow passage to detour the compressor, and a bypass valve provided on the bypass flow passage, includes closing the first on-off valve while driving the compressor, opening the bypass valve simultaneously with or after the closing of the first on-off valve, closing the second on-off valve after the opening of the bypass valve, and continuing to drive the compressor after the closing of the second on-off valve.

The present disclosure relates to a drain pump driving apparatus and a laundry treatment machine including the same. A drain pump driving apparatus according to an embodiment of the present disclosure includes a controller configured to drive a motor, during drainage, based on an output current and a direct current (DC) terminal voltage with a first power when a lift is at a first level and to drive the motor with the first power when the lift is at a second level that is greater than the first level, wherein the lift is a difference between a water level of a water introduction part through which water flows into a drain pump and a water level of a water discharge part through which the water is discharged out of the drain pump. Accordingly, water pumping can be performed smoothly even if the lift is changed during the drainage.

A rig management system is disclosed. The rig management system may be configured to receive information to be used to control shifting of a transmission to prevent cavitation during use of the hydraulic fracturing rig. The rig management system may be configured to determine a flow rate for a pump based on the information. The rig management system may be configured to determine an output torque of the transmission based on the flow rate. The rig management system may be configured to determine a transmission gear for the transmission based on the output torque and a fuel consumption map, wherein the fuel consumption map identifies a respective fuel consumption rate for different combinations of transmission gears and output torques. The rig management system may be configured to cause the transmission to shift into the transmission gear after determining the transmission gear.

A method for controlling a compression system that includes a compressor for compressing gas, a first on-off valve provided on a suction flow passage connected to a suction side of the compressor, a pressure reducing valve provided on a portion of the suction flow passage upstream of the first on-off valve, a second on-off valve provided on a discharge flow passage connected to a discharge side of the compressor, a bypass flow passage connecting the suction flow passage and the discharge flow passage to detour the compressor, and a bypass valve provided on the bypass flow passage, includes closing the first on-off valve while driving the compressor, opening the bypass valve simultaneously with or after the closing of the first on-off valve, closing the second on-off valve after the opening of the bypass valve, and continuing to drive the compressor after the closing of the second on-off valve.

The disclosure discloses a method and a device for controlling cylinder switching of a compressor, a unit and an air conditioning system. The method includes: determining whether the compressor needs to perform cylinder switching; if so, adjusting current operating frequency according to a system pressure difference so that both the adjusted operating frequency and the system pressure difference meet a cylinder switching condition of the compressor; and controlling the compressor to perform cylinder switching. At the moment, the system pressure difference and the operation frequency are stable, and would not interfere the compressor's maintaining of the single-cylinder or double-cylinder operation state, which guarantees the energy efficiency of the unit where the compressor is located, and improves the use experience of a user.