Chapter 8, Problem 8.11P

Show an external data to support the claim that the consumers living within regions with hot climate will buy the stainless steel pan with digital thermometer reading that is powered by the heat generated while cooking and that sales will be higher in summer.

6.81 An industrial process involves evaporation of a thin water film from a contoured surface by heating it from below and forcing air across it. Laboratory measure- ments for this surface have provided the following heat transfer correlation: 0.58 NuL = 0.43 Re8 P04 The air flowing over the surface has a temperature of 290 K, a velocity of 10 m/s, and is completely dry ( = 0). The surface has a length of 1 m and a surface area of 1 m². Just enough energy is supplied to maintain its steady-state temperature at 310 K. (a) Determine the heat transfer coefficient and the rate at which the surface loses heat by convection. (b) Determine the mass transfer coefficient and the evaporation rate (kg/h) of the water on the surface. (c) Determine the rate at which heat must be supplied to the surface for these conditions.

5. A 500 m dark-colored swimming pool is located in a well-sheltered site where the measured wind speed at 10m height is 3 m/s. The water temperature is 25 °C, the ambient air temperature is 17 °C, and relative humidity is 60%. There are no swimmers in the pool, the temperature of the make-up water is 22 °C, and the solar irradiation on a horizontal surface for the day is 20.2 MJ/m? day. The amount of energy must the solar system supply (GJ/d) is: a) 4.731 b) 5.729 c) 6.234 d) 8.338

A food product with 82% moisture content is being frozen. Estimate the specific heat of the product at -8°C when 82% of the water is in a frozen state. The specific heat of dry product solid is 2.5 kJ/(kg °C). Assume specific heat of water at -10°C is similar to specific heat of water at 0°C.

calculate the convection heat transfer rate over a surface of area 1 m^2 having heat convection coefficient of 40 W/m^2K and temperature difference of 25 °C

A mass of 300kg of oil is cooled in 1 hour from 70 celcius to 35 celcius in a cooler consisting of a bank of tubes through which hot oil passes. Cooling water circulates around the outside of the tubes. Calculate the mass of cooling water required per hour if the water temp increases by 21 degrees celcius . Specific Heat of Oil - 2.0 kJ/kg deg C Specific Heat of Water - 4.186 kJ/kg deg C

How long should it take to boil an egg? Model the egg as a sphere with radius of 2.3 cm that has properties similar to water with a density of = 1000 kg/m3 and thermal conductivity of k = 0.606 Watts/(mC) and specific heat of c = 4182 J/(kg C). Suppose that an egg is fully cooked when the temperature at the center reaches 70 C. Initially the egg is taken out of the fridge at 4 C and placed in the boiling water at 100 C. Since the egg shell is very thin assume that it quickly reaches a temperature of 100 C. The protein in the egg effectively immobilizes the water so the heat conduction is purely conduction (no convection). Plot the temperature of the egg over time and use the data tooltip in MATLAB to make your conclusion on the time it takes to cook the egg in minutes.

1.67 In beauty salons and in homes, a ubiquitous device is the hairdryer. The front end of a typical hairdryer is idealized as a thin-walled cylindrical duct with a 6-cm diameter with a fan at the inlet that blows air over an electric heating coil as schematically shown in the figure. The design of this appliance requires two power settings, with which the air blown over the electric heating coil is heated from the ambient temperature of to an outlet temperature of and with exit air velocities of 1.0 m/s and 1.5 m/s. Estimate the electric power required for the heating coil to meet these conditions, assuming that heat loss from the outside of the dryer duct is neglected.

Discuss the environmental impact of fixed and rotary aircraft during flight