Split cycle internal combustion engine

1. A split cycle internal combustion engine apparatus, comprising:

a combustion cylinder accommodating a combustion piston;

a compression cylinder accommodating a compression piston and being arranged to provide compressed fluid to the combustion cylinder, the compression cylinder being coupled to a first liquid coolant reservoir and a second liquid coolant reservoir; and

a controller arranged to receive an indication of at least one parameter associated with the engine, and control delivery of at least one of a first liquid coolant from the first liquid coolant reservoir and a second liquid coolant from the second liquid coolant reservoir to the compression cylinder based on the indication of the at least one parameter such that the at least one liquid coolant vaporises into a gaseous phase during a compression stroke and a rise in temperature caused by the compression stroke is limited by the absorption of heat by the at least one liquid coolant;

wherein controlling delivery of at least one of the first liquid coolant and the second liquid coolant comprises at least one of:

controlling the timing of the delivery of at least one of the first liquid coolant and the second liquid coolant relative to a position of the compression piston based on the indication of the at least one parameter;

controlling the ratio of delivery of the first liquid coolant to the second liquid coolant based on the indication of the at least one parameter.

2. The apparatus of claim 1 wherein the first liquid coolant comprises liquid nitrogen.

3. The apparatus of claim 1 wherein the controller is configured to control delivery of both the first liquid coolant and the second liquid coolant to the compression cylinder.

4. The apparatus of claim 1 wherein the combustion cylinder is further coupled to a third liquid reservoir for providing a source of fuel for a combustion process in the combustion cylinder.

5. The apparatus of claim 4 wherein the controller is configured to control delivery of the fuel to the combustion cylinder based on an indication of at least one parameter associated with the engine.

6. The apparatus of claim 5 wherein the controller is configured to control delivery of the fuel to the combustion cylinder based on the temperature of an exhaust emitted from the combustion cylinder.

7. The apparatus of claim 4 wherein the controller is configured to control delivery of the fuel to the combustion cylinder based on the current operating RPM of the combustion cylinder.

8. The apparatus of claim 4 wherein the controller is configured to receive a demand signal, and wherein the controller is configured to control delivery of fuel to the combustion cylinder based on the received demand signal.

9. The apparatus of claim 1 wherein the indication comprises a demand signal, and wherein the controller is configured to control delivery of at least one of the first liquid coolant from the first liquid coolant reservoir and the second liquid coolant from the second liquid coolant reservoir to the compression cylinder based on the demand signal.

10. The apparatus of claim 1 , wherein the first liquid coolant comprises a liquid coolant condensed into a liquid phase via a refrigeration process, and the second liquid coolant comprises water.

11. The apparatus of claim 10 wherein the at least one parameter comprises a water saturation level, and wherein the controller is configured to increase the ratio of the first liquid coolant to the compression cylinder relative to the second liquid coolant in response to the water saturation level reaching a water saturation threshold.

12. The apparatus of claim 11 wherein the controller is configured to increase the ratio of the second liquid coolant to the compression cylinder relative to the first liquid coolant in response to the water saturation level being below the selected water saturation threshold.

13. The apparatus of claim 1 wherein the at least one parameter comprises a temperature in the compression cylinder, and wherein the controller is configured to reduce the delivery of the first liquid coolant and the second liquid coolant to the compression cylinder in response to the indication of the temperature in the compression cylinder being below a selected temperature threshold.

14. The apparatus of claim 1 wherein the at least one parameter comprises a pressure in the compression cylinder, and wherein the controller is configured to reduce the delivery of the first liquid coolant and the second liquid coolant to the compression cylinder in response to the indication of the pressure in the compression cylinder being below a selected pressure threshold.

15. The apparatus of claim 1 wherein the compression cylinder comprises an inlet port for the admission of air and wherein the controller is configured to control operation of the inlet port to control the ratio of air to the ratio of the first liquid coolant and/or the second liquid coolant based on the indication of the at least one parameter.

16. The apparatus of claim 1 wherein the compression cylinder comprises an outlet port and the combustion cylinder comprises an inlet port coupled to the outlet port of the compression cylinder via a recuperator for receiving a compressed fluid therefrom, wherein the recuperator is arranged to control the temperature of the compressed fluid delivered to the combustion cylinder, and wherein the at least one parameter comprises at least one of a temperature, a pressure or an oxygen concentration of the fluid in the recuperator.

17. A split cycle internal combustion engine apparatus, comprising:

a combustion cylinder accommodating a combustion piston;

a compression cylinder accommodating a compression piston and being arranged to provide compressed fluid to the combustion cylinder, the compression cylinder being coupled to a first liquid coolant reservoir and a second liquid coolant reservoir; and

a controller arranged to receive an indication of at least one parameter associated with the engine, and control delivery of at least one of a first liquid coolant from the first liquid coolant reservoir and a second liquid coolant from the second liquid coolant reservoir to the compression cylinder based on the indication of the at least one parameter such that the at least one liquid coolant vaporises into a gaseous phase during a compression stroke and a rise in temperature caused by the compression stroke is limited by the absorption of heat by the at least one liquid coolant;

wherein the at least one parameter comprises an oxygen saturation level and wherein the controller is configured to reduce the delivery of the first liquid coolant and the second liquid coolant to the compression cylinder in response to the indication of the oxygen saturation level being below a selected oxygen saturation threshold.

18. A method of operating a split cycle internal combustion engine apparatus, comprising:

receiving an indication of at least one parameter associated with the engine;

determining a quantity of a first liquid coolant and a second liquid coolant to inject into a compression cylinder of the split cycle internal combustion engine based on the received indication; and

controlling the delivery of at least one of the first liquid coolant and the second liquid coolant to the compression cylinder based on the determination such that the at least one liquid coolant vaporises into its gaseous phase during a compression stroke and a rise in temperature caused by the compression stroke is limited by the absorption of heat by the liquid coolant;

wherein controlling delivery of at least one of the first liquid coolant and the second liquid coolant comprises at least one of:

controlling the timing of the delivery of at least one of the first liquid coolant and the second liquid coolant relative to a position of the compression piston based on the indication of the at least one parameter;

controlling the ratio of delivery of the first liquid coolant to the second liquid coolant based on the indication of the at least one parameter.