Mitsubishi triples heat exchanger performance

JAPAN: Mitsubishi Electric claims to have developed a plate heat exchanger for heat pumps with a heat transfer performance triple that of its conventional grooved-plate heat exchangers.

The new heat exchanger is said to reduce the number of plate layers allowing the refrigerant charge to be reduced to approximately one-third that of conventional levels.

The move to flammable lower GWP refrigerants make it essential to minimise their volume to reduce the danger of accidental leaks. 

Mitsubishi Electric argues that although increasing heat transfer performance reduces the refrigerant charge, conventional heat exchangers with grooved plates perform insufficiently. Inserting micro-offset fins – which promote turbulence and heat transfer – between the flat plates was considered, but tests confirmed that the refrigerant’s gas-liquid two-phase flow does not distribute uniformly across an entire plate.

Instead, Mitsubishi Electric’s new plate heat exchanger has distribution channels at the fluid inlets and outlets that ensure uniform refrigerant flow across plates, even those fitted with micro-offset fins. The result is said to be an even distribution of gas-liquid two-phase flow refrigerant. 

Channel placement was optimised using proprietary analysis technology that simulates the complex flow of two-phase refrigerants.

According to be Mitsubishi, the technology could  be applied to a wide range of products, including water-based cooling and heating equipment, heat pump systems for electric vehicles and air-cooled air conditioners.