Masters Theses

Date of Award

8-1981

Degree Type

Thesis

Degree Name

Master of Science

Major

Mechanical Engineering

Major Professor

Robert Reid

Committee Members

Robert Reid, Dan Roeder, David Chaffin

Abstract

The performance of a 111-m2 passive solar modular house located on The University of Tennessee campus was modeled by a modified version of the computer program TRNSYS. A computer model was written and experimentally verified for the 20 clear water-filled tubes in the house.

The test house was supplied by the Tennessee Valley Authority (TVA) for study to determine the system's performance both experimentally and analytically. The building is a heavily-instrumented version of one of several passive designs that TVA has approved as a part of its incentive program to make passive solar modular homes available to the public. The five-room house is of conventional wood construction, well insulated, and tightly built. The passive heating system consists of 14.66 m2 of south-facing glass fitted with insulating shades and 20 water-filled tubes. Each tube is 0.305 m in diameter and 2.13 m tall and made from a fiberglass material. Various temperatures throughout the house and weather data at the test site have been collected each hour since April 15, 1981. These items are recorded by a computerized data acquisition system.

The house was simulated using subroutines supplied by TRNSYS representing components of the system. Experimental work was used to verify parts of the model not supplied with TRNSYS. A subroutine used to convert solar radiation measured at 45 degrees, as was done at the test site, to horizontal radiation as required by the computer program was verified from experimental information supplied by TVA. The portion of the tube model used to determine the amount of solar radiation transmitted by the water was independently verified at the test site by a system of pryanometers. Finally, the tube model itself was verified by comparing predicted and measured temperatures of the water in the tubes for a period of 504 hours. This verification showed the tube model predictions to be within three percent of the measured data.

Using heating season data from a typical year, the performance of the system and several alternatives was simulated. The house, as de-signed, required ten percent less auxiliary energy than the same house without water tubes, and 46 percent less energy than the same house with conventional amounts of south glass and no tubes or night insulation. An examination of the need for window insulation, used during the night, showed that the shades reduced the need for auxiliary heat by 24 percent.

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