From Commercial Ground-Source Heat Pump Systems
TEST RESULTS FIRST STAGE
Testing was performed in a psychrometric room. All temperatures were measured with 1000 ohm platinum RTDs. Airflow was measured with a 12-by 8-in. (30 by 20 cm) venturi. Water flow was measured with a brass venturi. All points were converted to a low-voltage DC signal and sent to a 38-channel A to D converter. A microcomputer processed this information and calculated and displayed temperatures, flow rates, relative humidities, air-side capacities, power inputs, and efficiencies. Test results were very encouraging. Cooling efficiencies range from a high of EER=27.6 (COP=8.1) in low speed with 75 F (24 C) entering liquid temperature (ELT) to EER=14.0 in 3/4 speed with 85 F (29 C) ELT. The unit attained a capacity of 37.9 MBtuh (11.1 kW) in 3/4 speed; therefore, it was not operated at full speed in cooling. This speed typically has a very high demand due to the high operating speed. More detailed information is included in Table 2. Heating performance was also good but not as impressive as cooling. COPs ranged from 6.0 in low speed with 55 F (13 C) ELT to 3.1 at full speed with 35 F (2 C) ELT. High-speed capacities ranged from 31.0 MBtuh (9.1 kW) with 35 F (2 C) ELT to 35.1 MBtuh (10.3 kW) with 55 F (13 C) ELT. Detailed information is included in Tables 3 and 4.
Entering Air Temp.
Flow rate (GPM)
Air Vol. (CFM)
Entering Water Temp.
Total Cool. (MBtuh)
Sen. Cool. (MBtuh)
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Topics of Interest
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