Heat transfer from earth-coupled heat exchangers-Experimental and analytical results
Experimental heat transfer results obtained with tubular heat transfer coils buried in soil are presented along with a finite difference simulation model that predicts the heat transfer to or from the buried pipes and the temperature distribution in the soil surrounding the buried pipes. The results were obtained with two different earth-coupled coils. Each coil was fabricated from 2.2 in. (5.6 cm) ID nominal 2 in. diameter cast iron pipe. The length of the heat exchanger for each earth-coupled system was 90 ft. (27.4 m). The earth-coupled coils were buried at a depth of 2.75 ft. (0.84 m) below the surface of the earth. The experimental data cover a time span of seven months and represent operation of the earth-coupled coils at various heat rates. Some of the prime quantities measured on a continuous basis are the earth's temperature at several locations in the vicinity of the buried coils, the far earth temperature, the solar insolation, moisture content of the soil, and the heat transferred to or from the buried coils to the surrounding soil. The finite difference model tracks the temperature distribution in the earth surrounding the coils on a continuous basis and predicts the earth's temperature at many locations adjacent to the earth-coupled coil with a maximum error of 4/sup 0/F (2.2/sup 0/C) during the seven month test. As parameters, the finite difference model included the moisture content of the soil, convection at the surface of the earth, emissivity of the soil, radiation exchange at the air-soil interface, as well as all of the pertinent parameters related to the flow of the heat transfer fluid through the buried pipes. The results presented, both experimental and simulated, have direct application in the design of earth-coupled water-source heat pump systems.
- Research Organization:
- Mechanical and Aerospace Engineering, North Carolina State Univ., NC
- OSTI ID:
- 5409808
- Report Number(s):
- CONF-850606-
- Journal Information:
- ASHRAE Trans.; (United States), Vol. 91:2B; Conference: American Society of Heating, Refrigerating and Air-Conditioning Engineers' semiannual meeting, Honolulu, HI, USA, 23 Jun 1985
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GROUND SOURCE HEAT PUMPS
HEAT TRANSFER
SOILS
TEMPERATURE MEASUREMENT
CAST IRON
CONVECTION
DISTANCE
EMISSIVITY
EXPERIMENTAL DATA
FINITE DIFFERENCE METHOD
FLUID FLOW
FORECASTING
HEAT EXCHANGERS
HEAT TRANSFER FLUIDS
HEATING RATE
INSOLATION
LENGTH
MATHEMATICAL MODELS
MOISTURE
PIPES
TEMPERATURE DISTRIBUTION
ALLOYS
CARBIDES
CARBON COMPOUNDS
DATA
DIMENSIONS
ENERGY TRANSFER
FLUIDS
HEAT PUMPS
INFORMATION
IRON ALLOYS
IRON BASE ALLOYS
IRON CARBIDES
IRON COMPOUNDS
ITERATIVE METHODS
MASS TRANSFER
NUMERICAL DATA
NUMERICAL SOLUTION
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
SURFACE PROPERTIES
TRANSITION ELEMENT COMPOUNDS
320100* - Energy Conservation
Consumption
& Utilization- Buildings