PROGRAMMING THE BLOWER IN CA STORAGES 



Wien apples have been placed in CA storage in Massachusetts, the usual 

 practice is to allow the evaporator blower to run continuously to insure uniform 

 temperatures and uniform air composition throughout the storage. The necessity 

 for this continuous blower operation has been questioned as less electricity 

 would be needed to operate a blower intermittently. Since heat is added to the 

 storage whenever the blower circulates air, additional savings accrue because the 

 refrigeration system can operate for shorter periods and still maintain proper 

 storage temperatures. Operating the blower intermittently rather than contin- 

 uously, is termed "programming" the blower. Blowers may be programmed in various 

 ways. One of the simplest and easiest ways is for the blower to run only when 

 the control thermostat calls for the refrigeration system to operate to remove 

 heat from the storage. 



To investigate the feasibility of programming blower operations with the 

 refrigeration control thermostat, observations were made in the fall of 1959 

 on two similar 12,000 box storages. The blower in one storage was programmed 

 while that in the second operated continuously. In October the programmed 

 blower operated 45 per cent of the time and in November, 16 per cent of the time. 

 It was estimated that a $30.00 savings in electrical costs was realized in this 

 period. Analyses of composite apple samples indicated that the reduced air 

 circulation did not effect the quality of the fruit in storage. Furthermore, 

 periodic temperature measurements in the two storages by means of thermocouples 

 indicated a satisfactory uniform temperature distribution within 2°F throughout 

 the storages. 



Observations on the same two 12,000 box storage rooms from January 18, 1961 

 to February 16, 1961 indicated that the blower operated only 13.2 per cent of 

 the time. This was not considered typical, however, because of an extended cold 

 period. The total number of times the blower was "off" during this period was 

 16 with the longest "off" period being 18.1 hours. Composite samples from these 

 two storages, one of which was programmed for the entire storage season, 

 indicated no observable difference in quality of fruit. For the two months of 

 operation observed, it is estimated that for the blower alone, $12-15 savings per 

 month in electrical energy was realized. 



In a comparison of two 30,000 box CA storage rooms in which the blower in 

 one of the storages was programmed with the refrigeration thermostat, it was 

 observed that between November 29, 1960 and January 17, 1961, the programmed 

 blower operated 60.5 per cent of the time. The maximum length of "off" period 

 was 23.6 hours. The construction of these storages, however, is not typical of 

 Massachusetts so that this data must be considered as approximate. Temperature 

 measurements within the storages by means of thermocouples located both in air 

 and within apples within the storages indicated no observable difference in 

 temperature variations. Composite samples of apples from the two storages indi- 

 cated no difference in quality of the apples from these two storages. 



These limited data so far obtained indicate that it is feasible to program 

 blowers in CA storages. Additional information is needed before firm recommen- 

 dations can be safely established. Observations are to be continued during the 

 coming storage season. 



John S. Perry 



Associate Professor 

 Agricultural Engineering 



