Steam generation unit using a heat exchanger

A heating, ventilation, air conditioning, and refrigeration (HVACR) system comprising:

• a refrigerant circuit including a compressor, a steam generation unit, an expander, and an evaporator fluidly connected, the refrigerant circuit including a working fluid, the steam generation unit configured to heat the first process fluid using the working fluid compressed by the compressor, the refrigerant circuit including a refrigerant, wherein
• a steam generation unit includes:
• a mixed-phase heat exchanger including:
• a shell and end plates for receiving a process fluid in a volume defined by the shell and the end plates, the shell including a process fluid inlet at a bottom of the shell for receiving the process fluid and a process fluid outlet at a top of the shell for discharging the process fluid, and
• channels disposed inside the shell that extend between the end plates to pass a working fluid for heat exchange with the process fluid in the volume of the shell,
• wherein the shell and the channels are configured to define at least a first heat exchange zone comprising a first pass of the channels for preheating the process fluid in the volume of the shell, a second heat exchange zone comprising a second pass of the channels for boiling the process fluid in the volume of the shell, and a third heat exchange zone comprising a third pass of the channels for superheating the process fluid in the volume of the shell, and
• wherein the steam generation unit is configured to heat the process fluid sequentially from the first heat exchange zone to the second heat exchange zone to the third heat exchange zone, and
• wherein the third pass of the channels includes a working fluid inlet that is configured to receive the working fluid and the first pass of the channels includes a working fluid outlet that is configured to return the working fluid.