Question

In: Mechanical Engineering

Water is to be heated from 12◦C to 70◦C as it flows through a 2 centimeter...

Water is to be heated from 12◦C to 70◦C as it flows through a 2 centimeter internal diameter, 7 meter 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 of the heat generated in 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 power rating of the resistence heater. Also, estimate the inner surface temperature of the pipe at the exit.

Solutions

Expert Solution


Related Solutions

The water in a 40-L tank is to be heated from 15°C to 45°C by a...
The water in a 40-L tank is to be heated from 15°C to 45°C by a 25-cm-diameter spherical heater whose surface temperature is maintained at 85°C. Determine how long the heater should be kept on. Given: The properties of air at 1 atm and the film temperature of 57.5°C. Fluid temperature = Average temperature for water (15+45)/2=30°C k = 0.6515 W/m.°C, v = 0.493 x 10-6 m2/s, Pr = 3.12, and ? = 0.501 x 10-3 K-1 The properties of...
Water in an open metal drum is to be heated from 27 °C to 80 °C...
Water in an open metal drum is to be heated from 27 °C to 80 °C by adding superheated steam slowly enough that all the superheated steam condenses. The drum initially contains 250 kg of water, and superheated steam is supplied at 5.0 bar and 375 °C via a 7.5 cm ID stainless steel pipe. a.) How many kilograms of superheated steam should be added so that the final temperature of the water in the tank is exactly 80 °C?...
21. If a 2.50 mol sample of water is heated from -50 °C to 75 °C...
21. If a 2.50 mol sample of water is heated from -50 °C to 75 °C at a constant pressure of 1 atm, what is the change in enthalpy?
Water at a flow rate of 20,000 kg/h will be heated from 20°C to 35°C by...
Water at a flow rate of 20,000 kg/h will be heated from 20°C to 35°C by hot water at 140°C. A 15°C hot water temperature drop is allowed. A number of 3.5 m hairpins of 3 in. (ID = 0.0779 m) by 2 in. (ID = 0.0525 m, OD = 0.0603 m) counter flow double-pipe heat exchangers with annuli and pipes, each connected in series, will be used. Hot water flows through the inner tube. Fouling factors are: Rf i...
Calculate ΔS if 2.10 mol of liquid water is heated from 0.00 ∘C to 13.5 ∘C...
Calculate ΔS if 2.10 mol of liquid water is heated from 0.00 ∘C to 13.5 ∘C under constant pressure if CP,m=75.3J⋅K−1⋅mol−1. The answer the the problem above is 7.62 J/K The melting point of water at the pressure of interest is 0.00 ∘C, and the enthalpy of fusion is 6.010 kJ⋅mol−1. The boiling point is 100. ∘C, and the enthalpy of vaporization is 40.65 kJ⋅mol−1. Calculate ΔS for the transformation of the same amount of water H2O(s,0.00∘C) →H2O(g,100.∘C) Can you...
1000 L/h of oil is heated from 40C to 70 C in a 3 cm ID...
1000 L/h of oil is heated from 40C to 70 C in a 3 cm ID heated copper tube. The inner surface of the tube is maintained at 100 C. Since the temperature dependencies of the fluid are not given, the properties will be assumed constant. Assume the viscosity ratio equal one. The following physical property data are available for the oil. What is the length of the tube? ?? = 2090?/?? ? ? = 880 ??/?3 ? = 0.00062...
Water at 70°F flows by gravity from a large reservoir at a high elevation to a...
Water at 70°F flows by gravity from a large reservoir at a high elevation to a smaller one through a 55-ft-long, 2-in-diameter cast iron piping system that includes four standard flanged elbows, a well-rounded entrance, a sharp-edged exit, and a fully open gate valve. Taking the free surface of the lower reservoir as the reference level, determine the elevation z1 of the higher reservoir for a flow rate of 10 ft3/min. The density and dynamic viscosity of water at 70°F...
Water flowing at a rate of 0.03 kg/s is heated from 20 to 40°C in a...
Water flowing at a rate of 0.03 kg/s is heated from 20 to 40°C in a horizontal pipe (inside diameter = 3 cm). The inside pipe surface temperature is 70°C. Estimate the convective heat transfer coefficient if the pipe is 1 m long. Assume forced convection conditions.  Ts is not held constant! Properties of Water 20°C 30°C 40°C ρ (kg/m3) 998.2 995.7 992.2 k (W/mK) 0.597 0.615 0.633 μ (Pa s) 993.414 x 10-6 792.377 x 10-6 658.026 x 10-6 Cp...
Question 1) Water at 20 C flows through a galvanized pipe at an average speed of...
Question 1) Water at 20 C flows through a galvanized pipe at an average speed of 2.5 m / s. The diameter of the pipe is 150 mm. The roughness of the pipe surface is 60 μm. Calculate the pressure drop in this pipe since the total length of the pipe is 300 meters. Take the necessary values for calculations from tables and diagrams.
Water at a mean velocity of 0.2 m/s is heated from 20 to 40°C by passing...
Water at a mean velocity of 0.2 m/s is heated from 20 to 40°C by passing it through a 0.5-cm-ID tube. The 2 surface is heated with a uniform heat flux of 6000 W/m . Find the following: a) The length required to heat the water to a given temperature.,b) the surface temperature at the inlet of the tube. Given that the following information: The physical properties of liquid at 30 °C: ?? =4182?⁄??.°?,?=0.6405?⁄?.°?,??=3.57,?=0.5537×10−6?2⁄?,?=988??⁄?3
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT