You've experienced convection cooling if you've ever extended your hand out the window of a moving vehicle or into a flowing water stream. With the surface of your hand at a temperature of
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Introduction to Heat Transfer
- The air-conditioning system in a Chevrolet van for use in desert climates is to be sized. The system is to maintain an interior temperature of 20C when the van travels at 100 km/h through dry air at 30C at night. If the top of the van is idealized as a flat plate 6 m long and 2 m wide and the sides as flat plates 3 m tall and 6 m long, estimate the rate at which heat must be removed from the interior to maintain the specifiedarrow_forwardAn electrical transmission line of 1.2-cm diameter carries a current of 200 amps and has a resistance of 310-4 ohm per meter of length. If the air around this line is at v, determine the surface temperature on a windy day, assuming a wind blows across the line at 33 km/h.arrow_forward1.19 A cryogenic fluid is stored in a 0.3-m-diameter spherical container is still air. If the convection heat transfer coefficient between the outer surface of the container and the air is 6.8 , the temperature of the air is 27°C, and the temperature of the surface of the sphere is –183°C, determine the rate of heat transfer by convection.arrow_forward
- You’ve experienced convection cooling if you’ve ever extended your hand out the window of a moving vehicle or into a flowing water stream. With the surface of your hand at a temperature of 30degC, determine the convection heat flux for (a) a vehicle speed of 47 km/h in air at 5degC with a convection coefficient of 40 W/m^2-K and (b) a velocity of 0.4 m/s in a water stream at10degC with a convection coefficient of 900 W/m^2-K. Which condition would feel colder? Add filearrow_forwardIn a new residential project, you strongly believe thatdouble-paned windows are ‘better’ than single-paned windows.Compare the rate of heat loss between single and double-panedwindows (1.5 m x 1 m) if the thickness of each pane is (th = 0.4 cm)and (k = 0.9 W/m.K). The indoor and outdoor temperatures are 18°C and 2 °C, respectively. Thickness of the air gap between thedouble-paned windows is (th = 1 cm), and (k = 0.022 W/m.K).Image credit: Windowwhirl.arrow_forwardWhat is a semi-infinite medium? Give examples of solid bodies that can be treated as semi-infinite mediums for heat transfer purposes.arrow_forward
- 3- You have experienced convection cooling if you have ever extended your handout of the window of a moving vehicle or into a flowing water stream. With the surface of your hand at a temperature of 30 oC, determine the convection heat flux for a) a vehicle speed of 35 km/h in air at -5 oC with convection coefficient of 40 W/m2 .K and b) a velocity of 0.2 m/s in a water stream at 10 oC with convection coefficient of 900 W/m2.K. Which condition would feel colder? Contrast theseresults with a heat loss of approximately 30 W/m2 under normal room conditions.arrow_forwardThe shooter holds a leather-covered baseball for a certain period of time, bringing the outer surface temperature of the ball to 30 ℃. Then the shooter throws the ball at 80 km/h to another athlete standing 18.5 meters away. It is known that the diameter of the ball is 7 cm and the air temperature is 20 ℃. Calculate the total heat transfer from the ball to the ambient air during flight, in Joules, assuming that the outer surface temperature of the ball remains constant throughout the shot. (When finding the properties, find the real values by interpolating. Ignore the air resistance.)arrow_forwardAir at 300 degrees Celsius flows over a plate of dimension 0.5 m by 0.25 m. If the convection heat transfer coefficient is 250 Watts per Sq.m Kelvin, determine the heat transfer rate from the air to one side of the plate if the plate is to be maintained at 40 degrees Celsius.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning