Write your answer in 4 decimal places. DO NOT round off intermediate values. Water (Cp = 4180 J/kg-K) enters a 4-cm-diameter tube at 15°C at a rate of 0.06 kg/s. The tube is subjected to a uniform heat flux of 2500 W/m2 on the surfaces. The length of the tube required in order to heat the water to 45°C is m

Q1 a) What is the physical significance of Reynolds number? Write down 5 (five) factors that influence the convection heat transfer rates. b) Water is to be heated from 10°C to 80°C as it flows through a 2-cm-internal-diameter, 7-m- long tube. The tube is equipped with an electric resistance heater, which provides uniform heating throughout the surface of the tube. The outer surface of the heater is well insulated, so that in steady operation all the heat from the heater is transferred to the water in the tube. If the system is to provide hot water at a rate of 8 L/min, determine the convection heat transfer coefficient and temperature at the inner surface of the pipe at the exit. Q2 a) Consider heat transfer to oil flow inside a copper pipe. Is the pipe length affecting the heat transfer rate into the oil? Briefly explain. b) Used engine oil can be recycled by a patented reprocessing system. Suppose that such a system includes a process during which engine oil flows through a…

Water enters a 2.5-cm-internal-diameter thin copper tube of a heat exchanger at 15°C at a rate of 0.61 kg/s, and is heated by steam condensing outside at 115°C. If the average heat transfer coefficient is 950 W/m2.K, determine the length of the tube required in order to heat the water to 105°C. (Insert answer for Q (kW), TLMTD (°C) and L (m) ) kW °C m

Heat transfer is of critical importance in various industrial applications, including manufacturing. During machining, both the cutting tool and the workpiece will be significantly heated by friction heating. The heating of the cutting tool will reduce the tool hardness and strength, deteriorate the cutting quality, and shorten the tool life. Therefore, it is essential to prevent the overheating of the cutting tool during machining. Coolants are an instrumental part of machining to help cool the tool and the workpiece, provide lubricant, flush away chips, and prevent corrosion. The task of this project is to design the coolant to maintain the maximum machine tool temperature below 100 °C during the side milling process. As shown in the figure below, the machine tool has a diameter of 10 mm (D) and a length of 5 cm. The tool material is M2 high speed tool steel (T11302) and the workpiece is aluminum 6061. The spindle speed (w) is 2000 RPM and the cutting speed (v) is 50 mm/min. The feed…

A father and son conducted the following simple experiment on a hot dog which measured 12.5 cm in length and 2.2 cm in diameter. They inserted one food thermometer into the midpoint of the hot dog and another one was placed just under the skin of the hot dog. The temperatures of the thermometers were monitored until both thermometers read 20°C, which is the ambient temperature. The hot dog was then placed in 94°C boiling water and after exactly 2 min they recorded the center temperature and the skin temperature of the hot dog to be 59°C and 88°C, respectively. Assuming the following properties for the hot dog: r = 980 kg/m3 and cp = 3900 J/kg·K and using transient temperature charts, determine (a) the thermal diffusivity of the hot dog, (b) the thermal conductivity of the hot dog, and (c) the convection heat transfer coefficient.

There is a cylindical piece of nickel, that is 5 cm in diameter and 10 cm in length, that is initially at 20 degrees Celcius before being dropped into a hot fluid that is at 190 degrees Celcius.  Determine the amount of heat gained by the cylinder until its temperature rises to 80 degrees Celcius.  Show details in calculations and specify values retrieved from property tables.

Most automobiles have a coolant reservoir to catch radiator fluid that may overflow when the engine is hot. Such a radiator, made of copper, is filled to its 12-L capacity when at 10.0°C.  -What volume of radiator fluid, in liters, will overflow when the radiator and fluid reach their 99.5°C operating temperature, given that the fluid’s thermal coefficient of volume expansion is 400.0 × 10-6 / °C? The coefficient of volume expansion for copper is 5.1 × 10-5 /°C.

Determine the ratio of thermal conductivity for N2 at sea level (T = 300 K, P = 1 atm) versusthe lower stratosphere (T = 230 K, P = 0.25 atm).

The temperature at the inner and outer surfaces of a boiler wall made of 20 mm thick steel and covered with an insulating material of 5 mm thickness are 300° C and 50° C respectively. If the thermal conductivities of steel and insulating material are 58W/m'C and 0.116 W/m'C respectively, determine the rate of flow through the boiler

A steel rod, which is free to move, has a length of 200 mm and a diameter of 20 mm at a temperature of 15oC.  If the rod is heated uniformly to 115oC, determine the length and diameter of this rod to the nearest micron at the new temperature if the linear coefficient of thermal expansion of steel is                   12.5 x 10-6 m/m/C.  Is there a stress on the rod at 115oC?