Description

This paper describes steady-state performance simulations performed on a 3-ton R-22 split heat pump in heating mode. In total, 150 steady-state points were simulated, which covers refrigerant charge levels from 70% to 130% relative to the nominal value, the outdoor temperatures at 17°F (–8.3°C), 35°F (1.7°C) and 47°F (8.3°C), indoor air flow rates from 60% to 150% of the rated air flow rate, and two types of expansion devices (fixed orifice and thermostatic expansion valve [TXV]). A charge tuning method, which is to calibrate the charge inventory model based on measurements at two operation conditions, was applied and shown to improve the system simulation accuracy significantly over an extensive range of charge levels. In addition, we discuss the effects of using a suction line accumulator in modeling a heat pump system using either a fixed orifice or thermal expansion valve. Last, we identify the issue of refrigerant mass flow mal-distribution at low charge levels and propose an improved modeling approach.

Citation: ASHRAE Transactions, Volume 117, Part 2, Montreal, QC

Product Details

Published:

2011

Number of Pages:

13

File Size:

1 file , 1000 KB

Product Code(s):

D-ML-11-007