1. A bench assembly 



2. An inlet header 



3. 12 thermocouples to measure the temperature of the inlet 

 fluid going to each of the 12 heat exchangers 



4. An outlet header 



5. 12 thermocouples to measure the fluid outlet temperature 

 for the 12 heat exchangers 



6. 12 flow meters each with a valve for flow adjustment 



7. A 52-gallon electric water heater 



8. A circulating pump (Figure 6) 



9. All necessary piping and valves 



All exposed piping was jacketed with fiberglass insulation covered with 

 aluminum sheeting. Thermocouple (copper-constantan) outputs were fed to 

 two recorders located inside the adjacent building. When one of these 

 recorders failed during the first month of operation, both recorders 

 were replaced by a 24-channel strip chart recorder. 



The 12 heat exchangers were installed in random order on the test 

 facility; the test fluid (approximately 1:1 solution of engine anti- 

 freeze and tap water) was added to the system; and a checkout was started. 

 After it was determined that the system did not leak, the water heater 

 was set for 140°F (60°C)" and turned on. Each flow meter control valve 

 was adjusted so that the flow meter scale reading was 50%,*" or 0.39 gpm 

 (1.48 1/m), of liquid with a specific gravity of 1.054 at 130°F (54°C). 

 Operation of the equipment was checked at the beginning and close of 

 each working day. 



Heat loss across each exchanger was determined by recording the 

 inlet and outlet temperatures. The 24-channel strip chart recorder 

 produced a data point approximately every 3 minutes. Temperature dif- 

 ferences were read from the chart paper and entered on specially prepared 

 data forms, each of which had spaces for two sets of 13 or 14 temperature- 

 drop readings per heat exchanger. When the voluminous data obtained was 

 reviewed by a CEL mathematical statistician, he suggested that at approxi- 

 mately 1-month intervals 13 or 14 temperature-drop readings be averaged 

 for each heat exchanger. Thus, the exchangers could be ranked in decreas- 

 ing order of cooling efficiency. 



On completion of the operation, a review of the data indicated that 

 much more meaningful conclusions could be obtained by calculation of the 

 heat transfer rate for each heat exchanger approximately weekly, and at, 

 or near, a time when the ambient temperature was known. The time chosen 



"Compression temperature for Freon-12 is approximately 110°F (43.4°C) 

 and for Freon-11 is 120°F (48.9°C). 



~\Fluid velocity in 1-inch (2.54-cm) ID tubing was 0.16 ft/sec. 



