“Maekawa of industrial refrigerator manufacturer developed a high-efficiency refrigerator for H2 filling stations using CO2 as a refrigerant.

In H2 stations for filling at 70MPa heat generation by adiabatic compression occurs in the fuel tank to fill high pressure H2 gas into fuel cell vehicles (FCV). Therefore, it is necessary to precool H2 gas down to -33℃ or less.

So far, refrigerators of another type using brine for secondary cooling have been supplied by the company, but in order to cope with requirements for more high-efficiency and compact refrigerators for future H2 stations for commercial use, Maekawa developed the CO2 refrigerator for the first time in the world for application to H2 filling stations.

The product is characteristic in its adoption of R-404A for the primary refrigerant and the circulation in the pipe of CO2 liquid as the secondary refrigerant which was precooled down to -33℃ or less. It is a new system of indirect cooling to refrigerate H2 gas.

It is possible to save by means of reducing conveyance power down to one tenth or less by using CO2 for the secondary refrigerant instead of high-viscosity brine.

Youichi Hiraga, manager belonging to the Cryogenic Solution Group said, “In contrast to the brine-type system which requires power of about 20kW, the secondary refrigerant of CO2 uses power of only 1.0kW or so.” In addition, the use of a heat exchanger of shell and plate type embedded inside the container enables heat exchanging for even a little difference of temperature, making the unit more efficient. Furthermore, it employs low-noise specifications on the assumption of future installation H2 filling stations in the urban areas.

The company was proceeding with technical development in use of natural refrigerants and succeeded to develop an energy-saving refrigerator with CO2 as the secondary refrigerant for dedicated use in refrigerated warehouses in 2008. Based on the CO2 refrigeration system, the company put it into market for application to H2 filling stations.

Toshiaki Hattori, director in charge of the Technical Development Bloc says, “Envisioning the concept of 100 locations of H2 station in 2015 first of all, some proposals have already shown up, and we aim at adoption at more than 60 locations. Furthermore, our development of compact refrigerators is underway, so that easier introduction can be made into the H2 stations combined with gasoline stations.”