Systems and methods for determining startup pressure ratio for dynamic compressors

A system comprising:

• an evaporator having a first working fluid path and a first heat transfer fluid path thermally coupled thereto;
• a condenser having a second working fluid path and a second heat transfer fluid path thermally coupled thereto;
• a dynamic compressor fluidly coupled to the first working fluid path of the evaporator and the second working fluid path of the condenser, the dynamic compressor operable to compress a working fluid;
• a first temperature sensor positioned within the first heat transfer fluid path of the evaporator;
• a second temperature sensor positioned within the second heat transfer fluid path of the condenser;
• a controller connected to the dynamic compressor, the controller comprising a processor and a memory, the memory storing instructions that program the processor to:
• receive a command to begin operation of the dynamic compressor;
• receive a first heat transfer fluid temperature from the first temperature sensor;
• determine a first pressure at the first working fluid path of the evaporator based on the first heat transfer fluid temperature;
• receive a second heat transfer fluid temperature from the second temperature sensor;
• determine a second pressure at the second working fluid path of the condenser based on the second heat transfer fluid temperature;
• determine an estimated pressure ratio of the dynamic compressor from the first and second pressures;
• determine a speed setpoint of the dynamic compressor based on the estimated pressure ratio;
• and
• operate the dynamic compressor at the speed setpoint to compress the working fluid until a condition is met.