Evaporator apparatus

1. Evaporator apparatus for a refrigeration cycle of a refrigeration system, the evaporator apparatus comprising:

a primary evaporator pathway for a working fluid of the refrigeration cycle extending through a primary expansion device and a primary evaporator;

a secondary evaporator pathway for the working fluid in parallel with the primary evaporator pathway and extending through a secondary expansion device and a secondary evaporator;

a coolant circuit for cooling a device, wherein the secondary evaporator is configured for heat exchange between the working fluid and a process fluid of the coolant circuit; and

a controller configured to:

control the primary expansion device to maintain a target superheat of the working fluid at a primary control location downstream of the primary evaporator; and

control the secondary expansion device based on monitoring a temperature of the process fluid to maintain a target temperature of the process fluid at a coolant control location in the coolant circuit,

wherein the primary evaporator pathway and the secondary evaporator pathway converge at a confluence point upstream of the primary control location.

2. The evaporator apparatus according to claim 1 , wherein the coolant control location is downstream of the secondary evaporator, and at or upstream of the device to be cooled.

3. The evaporator apparatus according to claim 1 , wherein the device to be cooled is selected from the group consisting of: a prime mover; a battery; an inverter; a capacitor; a power electronics device and a climate-controlled compartment.

4. The evaporator apparatus according to claim 1 , wherein the primary evaporator pathway and secondary evaporator pathway originate from a distributor line and diverge from the distributor line at a branch point configured to deliver working fluid to the respective pathways from the distributor line of the refrigeration cycle.

5. The evaporator apparatus according to claim 1 , wherein the primary expansion device and/or the secondary expansion device is an electronic expansion valve.

6. The evaporator apparatus according to claim 1 , wherein the target superheat is between 0° C. and 2° C.

7. A refrigeration system comprising:

an evaporator apparatus including:

a primary evaporator pathway for a working fluid of the refrigeration cycle extending through a primary expansion device and a primary evaporator;

a secondary evaporator pathway for the working fluid in parallel with the primary evaporator pathway and extending through a secondary expansion device and a secondary evaporator;

a coolant circuit for cooling a device, wherein the secondary evaporator is configured for heat exchange between the working fluid and a process fluid of the coolant circuit; and

a controller configured to:

control the primary expansion device to maintain a target superheat of the working fluid at a primary control location downstream of the primary evaporator; and

control the secondary expansion device based on monitoring a temperature of the process fluid to maintain a target temperature of the process fluid at a coolant control location in the coolant circuit,

wherein the primary and secondary evaporator pathways form part of a refrigeration cycle of the refrigeration system located downstream of a condenser and upstream of a compressor,

wherein the primary evaporator pathway and the secondary evaporator pathway converge at a confluence point upstream of the primary control location.

8. The refrigeration system according to claim 7 , wherein the refrigeration cycle and the coolant circuit are configured to provide the working fluid and the process fluid to the secondary evaporator in a counter-current arrangement.

9. The refrigeration system according to claim 7 , wherein the refrigeration cycle is charged with a working fluid, wherein the working fluid comprises at least 50% carbon dioxide by weight.

10. The refrigeration system according to claim 7 , wherein the coolant circuit is charged with a process fluid, wherein the process fluid comprises at least 50% water by weight.

11. A method of operating evaporator apparatus for a refrigeration system, the method comprising:

conveying a working fluid along a first evaporator pathway and along a second evaporator pathway, wherein the first evaporator pathway extends through a primary expansion device and a primary evaporator and wherein the second evaporator pathway is in parallel with the primary evaporator pathway and extends through a secondary expansion device and a secondary evaporator;

conveying a process fluid around a coolant circuit including through the secondary evaporator, wherein the cooling circuit is configured to cool a device and wherein the secondary evaporator is configured for heat exchange between the working fluid and a process fluid of the coolant circuit;

controlling the primary expansion device to maintain a target superheat of the working fluid at the primary control location; and

controlling the secondary expansion device based on monitoring a temperature of the process fluid, to maintain a target temperature of the process fluid at the coolant control location,

wherein the primary evaporator pathway and the secondary evaporator pathway converge at a confluence point upstream of the primary control location.

12. A computer program comprising instructions which, when executed by a processor, cause a method in accordance with claim 11 to be carried out.

13. A computer-readable storage medium comprising instructions which, when executed by a processor, cause the processor to carry out a method in accordance with claim 11 .