Design and Fabrication of a cooling system for the Microfuse Stick Computer

Abstract

The design of new electronics is based on faster but small er and better devices. This comes at a cost of high-power densities and high operating temperatures. The temperature of a stick computer rises at a rate of 0.75℃/ min per application loaded. This translates into a temperature rise of 3.75℃/min when five applications are loaded i.e., average application load on normal use. The CPU can generate heat which can potentially accumulate beyond the maximum operating temperature of 85℃ when the stick computer is overloaded i.e., running more than five applications in the background. The desired operating temperature of a stick computer is between 40℃ to 65℃ and an increase of just 5℃ above this range takes two years off the life expectance. Additionally, heat causes thermal degradation of the polycarbonate plastic casing when exposed to such excessive temperatures. This project aims at the design and construction of a cooling system for the MicroFuse stick computer to reduce the heat generation during operation while considering the space and size constraints of the stick. It also includes analysis of the feasible cooling strategies for miniaturized computers which include; air cooling, thermal electric cooling, and refrigeration cooling. From analysis of the cooling strategies, air cooling was selected as the best cooling strategy due its reliability, higher cooling efficiency, lower power consumption, lower maintenance and installation costs and its system components have a better size compatibility with the stick computer space restriction. Major system components for air cooling include; cooling fan, heat sink and heat plate. For better air circulation, the above components were designed with in a well-ventilated space. The cooling fan selection was based on the length and height restrictions since a fan is a standard part i.e., length<40mm, height<7mm. Design of the heat sink and plate included material selection and aluminum was selected as the best material compared to copper and graphite due its reliability, durability, higher thermal conductivity, and higher specific heat capacity. From the heat flow simulations conducted using SolidWorks software, the average temperature of the stick when a cooling system was incorporated is 47℃ and the maximum temperature is 63℃. This was computed at an average of 5 applications running in the background. Heat accumulation during operation is caused by a number of other factors and one of these factors is the environment in which its operating. This project considered the operating evironment to be constantat ie., at room temperature and pressure. A user can however enhance cooling when abnormal temperature patterns are noticed by; using an external fan, avoid using it for extended periods, ensuring proper ventilation, and avoiding over-loading of the stick by closing applications not in use