Design, operation and performance of a ground coupled heat pump system in a cold climate

Conference · Thu Jan 01 04:00:00 EST 1981

OSTI ID:6471711

Metz, P D

A small, well insulated house on the BNL site has been equipped with a ground coupled heat pump space conditioning system. This paper describes the design and installation of the system and presents performance data for the first winter of operation, October 1980 to March 1981. The heating system heat requirement for the 3 bedroom 104 m/sup 2/ (1120 ft/sup 2/) house was measured to be about 9.5 x 10/sup 6/ J/C-day (5000 Btu/F-day) by using resistance heating of the house between February and May 1980. This leads to a design heat rate of about 3.4 kW (11.5 x 10/sup 3/ Btu/hr) at the local design temperature of -12 C (10 F). Based upon the underground heat flow computer program GROCS developed at BNL, an antifreeze filled serpentine earth coil was designed to just meet the building's design heating needs with an average brine temperature never less than 7 C (20 F). The 155 m (507 ft) long, 1.2 m (4 ft) deep serpentine earth coil made from nominal size 1-1/2 in. (actual O.D. 4.633 cm) medium density polyethylene pipe was installed by a local plumbing contractor using two different chain driven trenchers. A commercially available water-to-air heat pump was used with minor modifications. System performance has been monitored using killowat-hour meters, a Btu-meter, and a datalogger-microcomputer data acquisition system. The house temperature has been kept between 21 and 23 C (70 and 74 F) all winter despite outdoor temperaure as low as -24 C (-11 F). During the period November 20, 1980 to March 2, 1981 while the outdoor temperature averaged -2 C (28 F), the system extracted approximately 10.2 x 10/sup 9/ J (9.7 x 10/sup 6/ Btu) from the ground with an almost constant heat pump COP (coefficient of performance) averaging about 2.3 and a system COP of 2.2. No resistance heating was used. Ways in which the system could be improved and this efficiency significantly increased are discussed.

• Research Organization: Brookhaven National Lab., Upton, NY (USA)
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6471711
• Report Number(s): BNL-29625; CONF-810812-25; ON: DE81024257
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
320101* -- Energy Conservation
Consumption
& Utilization-- Residential Buildings-- (-1987)
BUILDINGS
COEFFICIENT OF PERFORMANCE
DATA
DESIGN
GROUND SOURCE HEAT PUMPS
HEAT PUMPS
HEATING LOAD
HOUSES
INFORMATION
INSTALLATION
OPERATION
PERFORMANCE TESTING
PIPES
RESIDENTIAL BUILDINGS
TESTING
WATER SOURCE HEAT PUMPS
WEATHER