USA: An R32 refrigerant drop-in test carried out on an existing 27kW R410A Daikin VRVlll system is reported to have shown improvements in both capacity and energy efficiency.
The test was carried out by Daikin on an existing system installed in offices in Plano, Texas, as part of the US Air-conditioning, Heating and Refrigeration Institute's low GWP Alternative Refrigerants Evaluation Programme.

The Japanese air conditioning manufacturer has championed the viability of R32 as a replacement for R410A and has introduced products in the Far East and India running on this 'mildly flammable' (A2L) refrigerant. So far, R32 is only offered in these countries in smaller residential units but Daikin has indicated in the past that it sees potential for its use in commercial systems.

R32 has a GWP of 650, significantly less than R410A's 1,980. Ironically, R32 is a major component of R410A, the other component of the blend, R125, merely suppresses R32's flammability.

The system under test comprises a Daikin RXYQ96PBTJ outdoor unit running 2 x 3.5kW and 4 x 5.3kW cooling capacity ducted fan coils. The outdoor unit uses an inverter-driven variable speed and a fixed speed scroll compressor and the six indoor units feature DC fan motors and direct-drive sirocco fans.

A baseline test of the system running on R410A was conducted prior to the replacement. The EER of the system was measured at 12.5 and the IEER (an indication of part load performance) was 17.

The charge of R32 was optimized to 8.98kg (83.2% of the R410A charge) to obtain the maximum cooling efficiency at the standard rating cooling test conditions.

Other than refrigerant change no other components were replaced and the system stayed the same as the R410A system.

The cooling capacity of R32 was found to be 2.9% higher and the EER was 6.4% higher than R410A at the standard-rating cooling conditions. The IEER part-load performance was even better, coming in 9.5% higher than R410A

R32 high and low temperature heating capacities were 4.8% and 2.4% higher than R410A respectively.

However, as previously reported, the discharge temperature of R32 is higher than R410A. In this test the discharge temperature was 16% higher in cooling, 15% higher in high temperature heating and nearly 20% higher in low temperature heating.

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