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Intelligent Cooler Controller
03 March 2015

We encourage students to send us synopses of their HVAC related projects, along with diagrams and photos, for publication in Student Corner. The Journal reserves the right to publish some of these synopses selectively. The Journal does not vouch for or endorse the accuracy of material published in this section – Technical Editor.

Aanand Nayyar, a student of Electrical Engineering at Dayalbagh Educational Institute, Agra has carried out a project to construct a working model of an evaporative cooler using a micro-controller to sense outside ambient conditions for optimum cooling. In an evaporative cooler, heat is absorbed by the evaporation of water circulating in the pads to cool the incoming air. The cooling so induced is sensitive to the Relative Humidity (RH) and the DBT of the incoming air. People often feel uncomfortable even with an evaporative cooler running. A scan of the market revealed that none of the evaporative coolers available provided for sensing of ambient conditions. This underscores the need for a device to sense outside ambient conditions to control the cooler’s operation. the lowest temperature the cooler pads can attain is the ambient WBT. Consequently, the control logic of the Intelligent Cooler Controller (ICC) senses the DBT and RH of incoming air and determines its WBT, which is theoretically the minimum temperature to which the cooler can cool. Please see Figure 1.

A working model has been constructed using a simple microcontroller, an RH and temperature sensor, relays, indicator LEDs and other components. Additional features, such as a water tank level sensor (beeps when tank is empty) and a manual override are also incorporated. Please see Figure 2. The ICC’s operation was evaluated across 240 cases covering the feasible range of operating combinations of RH and DBT. 38% of the cases corresponded to conventional cooler operation (both fan and pump on) with more than 80% of these providing eff ective cooling. 33% of the cases required only the fan to operate. In the remaining 29% cases the cooler is ineffective and the ICC switches off both the pump and the fan. This evaluation showed that the ICC improves comfort while providing savings. A report providing the complete design together with C source code is available for the benefi tof the industry [1]. The author may be contacted at aanandnayyar@gmail.com

References [1] ICC Report with C source code at www.coolingsmart.com


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