A new structural optimization method for distributors in R290 air conditioner with small diameter copper tubes.

R290 (propane) is one of the most potential natural working fluids due to its zero Ozone Depletion Potential (ODP) and low Global Warming Potential (GWP). However, the apply of R290 in air conditioner is inevitably limited because of its inflammability. The air conditioner with small diameter copper tubes can reduces refrigerant charge, ensuring the safety and reliability of R290 while increasing the flow paths can enlarges the risk of uneven distribution. Employing highperformance distributors ensures a uniform flow distribution for R290 room air conditioner (RAC). In this paper, a simulation-based structural optimization method has been investigated for distributor design, in which a mass flow distribution model has been verified and used for simulation. A new prototype based on this method is developed and experimentally tested in an air conditioner using R290 and 5mm diameter tubes, comparing with the conventional one. It is shown that the new prototype improves energy efficiency ratio as much as 2.2% under small air flow rate mode and 2.7% under large air flow rate mode. The experimental results validate the optimization effect of the structural method for distribution design in RAC.