Working fluid for heat cycle, composition for heat cycle system, and heat cycle system

1. A working fluid for heat cycle, comprising:

trifluoroethylene and 2,3,3,3-tetrafluoropropene,

wherein a total proportion of trifluoroethylene and 2,3,3,3-tetrafluoropropene based on an entire amount of the working fluid is from 70 to 100 mass %, and

a proportion of trifluoroethylene based on a total amount of trifluoroethylene and 2,3,3,3-tetrafluoropropene is from 35 to 95 mass %.

2. The working fluid according to claim 1 , wherein the total proportion of trifluoroethylene and 2,3,3,3-tetrafluoropropene based on the entire amount of the working fluid is from 80 to 100 mass %.

3. The working fluid according to claim 1 , wherein the proportion of trifluoroethylene based on the total amount of trifluoroethylene and 2,3,3,3-tetrafluoropropene is from 40 to 95 mass %.

4. The working fluid according to claim 1 , wherein a proportion of trifluoroethylene based on the entire amount of the working fluid is at most 70 mol %.

5. The working fluid according to claim 1 , further comprising: a saturated hydrofluorocarbon.

6. The working fluid according to claim 1 , further comprising: a hydrofluorocarbon comprising a carbon-carbon double bond other than trifluoroethylene and 2,3,3,3-tetrafluoropropene.

7. The working fluid according to claim 6 , wherein the hydrofluorocarbon comprising a carbon-carbon double bond is at least one selected from the group consisting of 1,2-difluoroethylene, 2-fluoropropene, 1,1,2-trifluoropropene, trans-1,2,3,3,3-pentafluoropropene, cis-1,2,3,3,3-pentafluoropropene, trans-1,3,3,3-tetrafluoropropene, cis-1,3,3,3-tetrafluoropropene, and 3,3,3-trifluoropropene.

8. The working fluid according to claim 6 , wherein the hydrofluorocarbon comprising a carbon-carbon double bond is trans-1,3,3,3-tetrafluoropropene.

9. The working fluid according to claim 5 , wherein the saturated hydrofluorocarbon is at least one selected from the group consisting of difluoromethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,2,2-tetrafluoroethane, 1,1,1,2-tetrafluoroethane, and pentafluoroethane.

10. The working fluid according to claim 5 , wherein the saturated hydrofluorocarbon is at least one selected from the group consisting of difluoromethane, 1,1,1,2-tetrafluoroethane, and pentafluoroethane.

11. The working fluid according to claim 10 , wherein

the saturated hydrofluorocarbon is difluoromethane,

based on a total amount of trifluoroethylene, 2,3,3,3-tetrafluoropropene, and difluoromethane, a proportion of trifluoroethylene is from 30 to 80 mass %, a proportion of 2,3,3,3-tetrafluoropropene is at most 40 mass %, and a proportion of difluoromethane is at most 30 mass %, and

a proportion of trifluoroethylene based on the entire amount of the working fluid is at most 70 mol %.

12. A composition for a heat cycle system, comprising:

the working fluid according to claim 1 and

a lubricating oil.

13. A heat cycle system, which employs the composition according to claim 12 .

14. The heat cycle system according to claim 13 , which is a refrigerating apparatus, an air-conditioning apparatus, a power generation system, a heat transport apparatus, or a secondary cooling machine.

15. The heat cycle system according to claim 13 , which is a room air-conditioner, a store package air-conditioner, a building package air-conditioner, a plant package air-conditioner, a gas engine heat pump, a train air-conditioning system, an automobile air-conditioning system, a built-in showcase, a separate showcase, an industrial fridge freezer, an ice making machine, or a vending machine.

16. The working fluid according to claim 1 , wherein the proportion of trifluoroethylene based on the total amount of trifluoroethylene and 2,3,3,3-tetrafluoropropene is from 44.4 to 95 mass %.

17. The working fluid according to claim 1 , wherein the proportion of trifluoroethylene based on the total amount of trifluoroethylene and 2,3,3,3-tetrafluoropropene is from 50 to 95 mass %.