From Commercial Ground-Source Heat Pump Systems


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.

Table 2: Test Results in Cooling Mode

(15% Methanol)

Test Run

Entering Air Temp.

Flow rate (GPM)

Air Vol. (CFM)

Entering Water Temp.

Total Cool. (MBtuh)

Sen. Cool. (MBtuh)


Power (kW)

Products & Services
Air Scrubbers, Wet Scrubbers, and Gas Scrubbers
Air scrubbers, wet scrubbers, and gas scrubbers are air pollution control devices that use a high-energy liquid spray to remove aerosol and gaseous pollutants from an air stream. The gases are removed either by absorption or chemical reaction.
Quenching Oils and Heat Treatment Fluids
Quenching oil and heat treatment fluids are designed for rapid or controlled cooling of steel or other metal as part of a hardening, tempering or other heat-treating process.
Cryostats and Dewars
Cryostats and dewars are used to keep sensors and store samples at very cold temperatures.
Compressed Air and Vortex Cooling Tubes
Compressed air and vortex cooling tubes are used for spot heating or cooling applications.
Cooling Towers
Cooling towers are defined as any open water recirculation device that uses fans or natural draft to draw or force air to contact and cool water by evaporation.

Topics of Interest

SECOND-STAGE DEVELOPMENT A major manufacturer of TEVs provided several valves it was felt would meet the needs of the VSGSHP based on the detailed data obtained during the first-stage testing.

At the time this article was written, Stephen P. Kavanaugh and Joey K. Parker were associate professors in the mechanical engineering department at the University of Alabama, Tuscaloosa. Robert S.

1.1 Turbines Combustion turbines used for electric power production are composed of two basic types. Industrial combustion turbines are usually referred to as single-shaft heavy-duty combustion...

CONTROLLER SOFTWARE A new control algorithm was designed to utilize the full range of variable-speed operation available from our control hardware. With the system controller, there are now 50...

These conversions are for those units most commonly encountered in cold-air distribution design. Additional information and conversions for other units are given in the ASHRAE publication, SI for...

New Privacy Policy

We have adopted new policies. Please read each one carefully.