Volume I - Section IV - Experimental Work and Verification of CFD Methodology 
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racks in two environmentally controlled chambers for acclimation. Both environmental chambers 
were kept at 24.0±1.5 °C (75.2±2.7 °F), but one was at 35±10 percent and the other at 75±10 
percent relative humidity (RH). The temperature and relative humidity in each chamber were 
continuously monitored with hygrothermographs (Oakton, model 37250-00). Cage litter was 
changed after the 3-day acclimation period, that was just prior to the 10-day test period. After the 
experiment, the mice were euthanized in a container precharged with carbon dioxide. 
4. 1.2. 3 Calorimeter design 
Three indirect, convective calorimeters were used for this project (see figure 4.33). A brief 
introduction to the indirect calorimeter is given in appendix I: section 3.1. A flow diagram of the 
calorimeter is shown in figure 4.34. Air temperature, velocity, and relative humidity were 
controlled in each calorimeter. The calorimeter boxes were constructed from 6.4e-3m (14”) thick 
plexiglass and were 0.356m high x 1.07m long x 0.585m deep (14” x 42.13” x 23”). Clear 
plexiglass was used to allow observation of animals and to allow light into the calorimeter from 
the environmental chamber. 
The entire front panel was removable to allow access of workers and to move mice in and out. 
The inside edges of the front panel were coated with vacuum grease to form a seal and were 
clamped on the calorimeter with 10 clamps around the perimeter. A recirculation pipe, 200mm 
diameter plexiglass tube, exited from one side of the calorimeter box, went up and over the 
calorimeter, and attached to an in-line fan on the other side of the calorimeter box. This air 
recirculation system allowed for the control of air velocity past the cages without affecting the 
fresh airflow exchange rate. 
Air Temperature Control 
The calorimeter box and air recirculation system were completely sealed to maintain the gas 
balance. Therefore, heat generated within the calorimeter had to transfer through the box or tube 
surfaces. To enhance this heat transfer process, all three calorimeters were placed within an 
environmental chamber that was operated at a lower temperature than the calorimeter air 
temperature. Also, a plastic duct, which served as a heat exchanger, was placed around the 
outside portion of the air recirculation tube and conditioned air was forced between that duct and 
the air recirculation tube to create a heat exchange system. One separate air conditioning/heating 
unit per calorimeter was placed outside the environmental chamber. Air from the tube heat 
exchange surface was recirculated through these units to control the temperature of the air 
passing through the heat exchanger and, thus, the amount of heat leaving or entering the heat 
exchanger. This heat exchange system, plus a 150W electric heater bar placed in the air 
recirculation tube, allowed for precise control of air temperature entering the calorimeter boxes. 
The heat exchanger, air conditioners, and heaters were controlled with a microprocessor PID 
temperature controller (Omega model CN9122A). Each calorimeter was individually controlled. 
Temperatures within the calorimeters were sensed with one type T thermocouple placed in the 
