Variable output heater control for unvented heaters used in livestock housing

Thumbnail Image
Date
1999
Authors
Van Utrecht, David Michael
Major Professor
Advisor
Hoff, Steve J.
Harmon, Jay
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Authors
Research Projects
Organizational Units
Journal Issue
Is Version Of
Versions
Series
Department
Abstract
Controlling temperatures in livestock buildings is critically important to ensure good health of the animal. Current housing systems utilize standard space heaters, with simple on/off control. This control scheme creates peaks and valleys in room temperatures as the thermostat seeks to maintain room temperature within a certain band around the set point. This process results in non-uniform temperatures in the barn, that depending on the pig age, could be a detriment to efficient growth. A typical unvented LP-gas space heater used in swine confinement buildings was modified to provide automated variable heat output. Initially, the unit had manually adjusted output settings between 50,000 and 100,000 BTU/hr. The heater was modified by adding a stepper motor to the proportioning valve to provide continuous and automated adjustment from 50,000 to 100,000 BTU/hr. Several experiments were conducted comparing animal occupied zone air velocities, room temperature uniformity, and fuel use of on/off control with automated variable control. The experiments were conducted in the Air Dispersion Laboratory at Iowa State University. Results indicate that adding automated variable valve control can significantly reduce temperature and air speed fluctuations in the building and consumes nearly the same amount of fuel as currently used onloff systems. Variable control reduced the difference between high and low temperatures by five degrees for a simulated nursery operated at 50 degrees F above ambient temperature. Variable control also maintained the average room temperature two degrees closer to the desired set point. Fuel consumption for this experiment was nearly identical. Results also indicate a need for heaters capable of continuous adjustment to a lower level.
Comments
Description
Keywords
Citation
DOI
Source
Copyright