As shown in Fig. P4.30, electronic components mounted on a flat plate are cooled by convection to the surroundings and by liquid water circulating through a U-tube bonded to the plate. At steady state, water enters the tube at 208C and a velocity of 0.4 m/s and exits at 248C with a negligible change in pressure. The electrical components receive 0.5 kW of electrical power. The rate of energy transfer by convection from the plate-mounted electronics is estimated to be 0.08 kW. Kinetic and potential energy effects can be ignored. Determine the tube diameter, in cm.
What is tribology Fundamentals of Tribology: • Surfaces in Contact • Friction • Lubrication • Wear •Two aspects – Science: Basic mechanisms – Technology: Design, manufacture, maintenance What is Tribology • Tribology is defined as the science of interacting surfaces in relative motion. • The word tribology comes from the Greek tribos, meaning rubbing. • In any machine there are lots of component parts that operate by rubbing together. • Some examples are bearings, gears, cams and tappets, tires, brakes, and piston rings. All of these components have two surfaces which come into contact, support a load, and move with respect to each other. • Sometimes it is desirable to have low friction, to save energy, or high friction, as in the case of brakes. Usually we don't wan