Water is to be heated as it flows through a carbon-silicon pipe of inner diameter 3 cm and wall thickness 5 mm. The outer surface of the pipe is wrapped in a thin electric resistance heater. The water enters the piping system at 20°C and this system is to supply water at 70°C at a rate of 10 L/min. a) The heater dissipates energy at a constant rate of 6 kW/m². The backside of the heater is well-insulated so that all this energy diffuses into the flowing water. Determine the required length of the pipe to meet the specified design criteria. Evaluate any necessary properties of water by treating the water as a saturated liquid at an appropriate average temperature. You can find properties of saturated water in Appendix A of the Bergman textbook. Also, you do not need to interpolate between temperatures on the table-simply use the table value that most closely matches your calculations. b) Determine the heater temperature at the end of the pipe assuming there is negligible contact resistance between the heater and the outer pipe wall. You can use a resistance network here but be careful with your units.

A camper has a propane-powered refrigerator. The refrigerator consumes approximately 0.50 kgof propane per day. When propane is burned completely, it releases approximately 50. MJ/kg.The interior of the refrigerator is maintained at an average temperature of 2.0 °C, and theexterior temperature is 22 °C. Assume that the refrigerator has a surface area of 2.0 m2 and thatthe insulation has an R-value of 3.2 K · m2/W.(a) At what rate does heat flow into the refrigerator?(b) At what rate must the refrigerator remove heat from its interior?(c) How much energy is released per second from the propane combustion?(d) How much heat is delivered to the room?

Consider two heat exchanger configurations: parallel-flow and counter-flow. For both configurations cooling water at a flow rate of 1.5 kg/s enters the heat exchanger at 30°C and exits at 45.1°C. This water cools unused engine oil at a flow rate of 1 kg/s from 95°C to 50°C. Both configurations have the same overall heat transfer coefficient of 9,000 W/m2/K. Determine the following: 1. What is the required heat transfer area for each configuration? 2. Give that both configurations have the same inlet and outlet temperatures, what is the basis of the different areas calculated in part a?

Question #7 Steam at 320°C flows in a stainless steel pipe (k-15W/m K) whose inner and outer diameter are 5cm and 5.5cm respectively. The pipe is covered with 3cm thick glass wool insulation (-0.038W/mK). Heat is lost to the surroundings at 5°C by natural convection and radiation, with a combined natural convection and radiation heat transfer coefficient of h 15W/m² K. Taking the heat transfer coefficient inside the pipe to be happe = outside pipe = 80 W/m²K. (A) Draw the schematic diagram of this problem and label all quantities. (B) Draw the thermal network diagram of this problem and label all thermal resistors and the direction of heat flow. (C) Determine the (i) inner surface area (ii) outer surface area (iii) inner thermal resis- tance (iv) outer thermal resistance (v) thermal resistance across pipe and (vi) thermal resistance across insulation. (D) Determine the total thermal resistance for the unit length of pipe. (E) Determine the rate of heat loss from the steam per unit…

determine the efficiency of the heat transfer process if a dry air parcel is heated by the earths surface at 15 c and rises adiabatically to the tropopause at -40 c. Assume the parcel follows the carnot cycle

A long thin-walled double-pipe heat exchanger with tube and shell diameters of 2 cm and 4 cm, respectively, is used to condense refrigerant-134a by water at 20 C. The refrigerant flows through the tube, with a convection heat transfer coefficient of hi = 4000 W/m2 K.A 1-mm-thick layer of limestone (k = 1.2 W/mK) forms on the outer surface of the inner tube. Water flows through the shell at a rate of 0.4 kg/s. Determine the overall heat transfer coefficient U of this heat exchanger with and without the fouling factor, and the error in U introduced by neglecting the fouling factor. Comment the fouling effect on this heat exchanger.

The condenser of a large thermal power plant is a body-tube type heat exchanger consisting of a single body and 30000 pipes with two passes each. The pipes are thin-walled with an inner diameter of 25 mm, and steam condenses on the outer surfaces of the pipes with a convection coefficient of 11000 W / m2.K. The heat transfer required by the heat exchanger is 2000 MW, and it is provided by the flow of water through the pipes at a flow rate of 30000 kg / h. Water enters at 20 ° C, steam condenses at 50 ° C. Calculate the temperature of the cooling water leaving the condenser? Determine the required pipe length per pass? The properties of water at Tort = 300 K; Cp = 4180 j / kgK, μ = 855 × 10--6 Ns / m2, k = 0.613 W / mK, Pr = 5.83.

A heat recovery device involves transferring energy from the hot flue gases passing through an annular region to pressurized water flowing through the inner tube of the annulus. The inner tube has inner and outer diameters of 24 and 30 mm and is connected by 8 struts to an insulated outer tube of 45-mm diameter. Each strut is 3 mm thick and is integrally fabricated with the inner tube from carbon steel (k = 50 W/m-K). D₂ D₁,2 Dil ↓ Water 1=3 mm Gas h Consider conditions for which water at 300 K flows through the inner tube at 0.161 kg/s while flue gases at 800 K flow through the annulus, maintaining a convection coefficient of 100 W/m².K on both the struts and the outer surface of the inner tube. What is the rate of heat transfer per unit length of tube from gas to the water? Use the Dittus-Boelter equation to obtain the water-side convection coefficient. Determine the rate of heat transfer per unit length of tube from gas to the water, in W/m. 9 = i W/m

Cold water (cp = 4180 J/kg×K) leading to a shower enters a thin-walled double-pipe counterflow heat exchanger at 15°C at a rate of 0.25 kg/s and is heated to 45°C by hot water (cp = 4190 J/kg×K) that enters at 100°C at a rate of 3 kg/s. If the overall heat transfer coefficient is 950 W/m2×K, determine the rate of heat transfer and the heat surface area of the heat exchanger using the effectiveness–NTU method.

A long counter-flow heat exchanger cools water from 40°C to 10°C by passing the water via the inner tube through an enclosure of cold fluid. The water is flowing through a 3-cm diameter tube at a rate of 0.27 kg/s. The cold fluid enters the enclosure at −10°C and has a convection coefficient of 1200 W/m².K. The mass flow rate of the cold fluid and its specific heat are 1.2 kg/s and 1340 J/kg-K, respectively. (a) Assuming the flow is fully developed, find out the convection coefficient of the water flow. (b) What is the length of the heat exchanger? 1554 W/m²K 2 21.9m Water Cold Fluid