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Title: TEMPERATURE AND HUMIDITY CONTROL IN INDIRECT CALORIMETER CHAMBERS

Author
item Brown-Brandl, Tami
item Nienaber, John
item Eigenberg, Roger

Submitted to: American Society of Agri Engineers Special Meetings and Conferences Papers
Publication Type: Other
Publication Acceptance Date: 7/19/2005
Publication Date: 7/19/2005
Citation: Brown Brandl, T.M., Nienaber, J.A., Eigenberg, R.A. 2005. Temperature and humidity control in indirect calorimeter chambers. American Society of Agri Engineers Special Meetings and Conferences Papers. Paper #054018.

Interpretive Summary: Indirect calorimetry is used to measure the heat and moisture production of livestock. The facility described in this paper is a modification of an original system built in the late 1970's. The paper describes a new set of animal chambers, pens, and air conditioning equipment to maintain desired temperatures and humidities. The humidity is controlled by cooling the air to the point of condensation and the condensed water is collected. The air is then heated to the desired temperature by electrical resistance heaters. Both temperature and humidity controllers are capable of operating with a constant or cyclic pattern over a 24-hr period. A stainless steel penning system was designed to collect all feces, urine, and waste water. Drinking water was delivered with a common nipple waterer within a cup to limit waste. The feeder was mounted on a load cell to allow constant monitoring of feed consumption. Pens were on wheels to give easy access to all areas of the pen for animal transport and pen cleaning. The entire calorimetry system was tested for accuracy by burning alcohol. The oxygen and carbon dioxide exchange during burning is similar to the exchange caused by an animal, and we know the exchange volumes by measuring the weight of alcohol burned. These tests verified that our system was accurate.

Technical Abstract: A three chamber indirect calorimeter has been a part of the Environmental Laboratory at the U.S. Meat Animal Research Center (MARC) for over 25 yr (Nienaber and Maddy, 1987). Corrosion of the animal chamber and unreliable temperature control has forced major repairs. There is a strong demand for heat production measurements; therefore, a new four chamber calorimetry system was designed and constructed. The chambers are both temperature and humidity controlled, with air handling units contained within each animal chamber to reduce air leak potential. Both temperature and humidity controllers are capable of cyclic and constant temperature patterns within a nominal range (10 to 40 C), and humidity control above 20% relative humidity. The objective of this paper is to describe the design of the chambers, heating system, cooling system, controllers with sensors, and the animal penning system. The existing gas analysis and data collection equipment was modified to accommodate four animal chambers.