Plasma spraying is a process used for coating a material surface with a protective layer to prevent the material from degradation. In a plasma spraying process, the protective layer in powder form is injected into a plasma jet. The powder is then heated to molten droplets and propelled onto the material surface. Once deposited on the material surface, the molten droplets solidi1y and form a layer of protective coating. Consider a plasma spraying process using alumina
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Heat and Mass Transfer: Fundamentals and Applications
- Plasma spraying is a process used to coat the surface of a material with a protective layer to prevent material degradation. In a plasma spray process, the protective coating in powder form is injected into a plasma jet. The powder is then heated until the droplets coalesce and are propelled over the surface of the material. Once deposited on the surface of the material, the molten droplets solidify and form a protective coating layer. Consider a plasma spray process using alumina (k = 30 W/m K, ρ = 3970 kg/m³ and cp = 800 J/kg K) powder that is injected into a plasma jet at T∞ = 15,000 ° C and h = 10,000 W/m²·K. Alumina powder is made up of spherical-shaped particles with a mean diameter of 60 μm and a melting point of 2300 °C.Solving, the amount of time it would take for the particles, with an initial temperature of 20 °C, to reach their melting point from the time they are injected into the plasma jet is 5,25x10 -4 s. Explain how the heat flow behaves in the system, using the…arrow_forwardPlasma spraying is a process used to coat the surface of a material with a protective layer to prevent material degradation. In a plasma spray process, the protective coating in powder form is injected into a plasma jet. The powder is then heated until the droplets coalesce and are propelled over the surface of the material. Once deposited on the surface of the material, the molten droplets solidify and form a protective coating layer. Consider a plasma spray process using alumina (k = 30 W/m K, ρ = 3970 kg/m³ and cp = 800 J/kg K) powder that is injected into a plasma jet at T∞ = 15,000 ° C and h = 10,000 W/m²·K. Alumina powder is made up of spherically shaped particles with a mean diameter of 60 μm and a melting point of 2300 °C. Determine the amount of time it would take for the particles, with an initial temperature of 20 °C, to reach their melting point from the time they are injected into the plasma jet. Note: Give the solution from fundamental concepts of how the heat flow…arrow_forwardPlasma spraying is a process used to coat the surface of a material with a protective layer to prevent material degradation. In a plasma spray process, the protective coating in powder form is injected into a plasma jet. The powder is then heated until the droplets coalesce and are propelled over the surface of the material. Once deposited on the surface of the material, the molten droplets solidify and form a protective coating layer. Consider a plasma spray process using alumina (k = 30 W/m K, ρ = 3970 kg/m³ and cp = 800 J/kg K) powder that is injected into a plasma jet at T∞ = 15,000 ° C and h = 10,000 W/m²·K. Alumina powder is made up of spherical-shaped particles with a mean diameter of 60 μm and a melting point of 2300 °C.Solving, the amount of time it would take for the particles, with an initial temperature of 20 °C, to reach their melting point from the time they are injected into the plasma jet is 5,25x10 -4 s. Give a solution from fundamental concepts of how the heat flow…arrow_forward
- A welding heat source is capable of transferring 160 kJ/min to the surface of a metal part. The heated area is approximately circular, and the heat intensity decreases with increasing radius as follows: 50% of the power is transferred within a circle of diameter = 0.25 cm and 75% is transferred within a concentric circle of diameter = 0.625 cm. What are the power densities in (a) the 0.25 cm diameter inner circle and (b) the 0.625 cm diameter ring that lies around the inner circle? (c) Are these power densities sufficient for melting metal?arrow_forwardA- Cylinder has a 0.1m in length and 0.1min diameter, is initially at 292 K. It is suspended in a steam environment where water vapor at 373 K condenses on all surfaces with an effective film coefficient, h, of 8500W/m2 K. Determine the time required for the center of this stubby cylinder to reach 310 K. If the cylinder were sufficiently long so that it could be considered infinite, how long would it take? (4 Marks)arrow_forwardA 20% (by wt) sodium hydroxide solution is being concentrated to 50% (by weight) using an evaporator at 311 K. The saturated steam used for heating is 399.3 K. The pressure in the vapor space of the evaporator is 13.3 kPa abs. If the overall heat transfer coefficient is 1420 W/m2-K and the area is 86.4 m2, calculate the feed rate of the evaporator.arrow_forward
- Steam condenses at 100°C on the outer surface of a pipe with a thermal conductivity of 180 J/ms°C. The surface heat transfer coefficient of the water flowing in the pipe is 4000 J/m²s°C, and the heat transfer coefficient created by the steam condensing outside is 10000 J/m²s°C. The length of the pipe is 5 m and the thread diameter is 25 mm. Since the pipe thickness is 1 mm, calculate the total heat transfer coefficient and the rate of heat transfer from the condensed steam to the water at 15 °Carrow_forwardThe condenser of a steam power plant operates at a pressure of 7.38 kPa (Tsat = 40°C). Steam at this pressure condenses on the outer surfaces of horizontal pipes through which cooling water circulates. The outer diameter of the pipes is 3 cm, and the outer surfaces of the pipes are maintained at 30°C. Determine the rate of condensation of steam per unit length of a horizontal pipe. The properties of water at the saturation temperature of 40°C are: hfg = 2407 × 10^3J/kg and ρv=0.05 kg/m3. The properties of liquid water at the film temperature: ρl = 994 kg/m3, Cpl =4178 J/kg°C, µl = 0.72 × 10^-3 kg/m.s, kl = 0.623 W/m°C Select one: a. 0.0026 kg/s b. 0.0046 kg/s c. 0.0016 kg/s d. 0.0036 kg/sarrow_forwardThe condenser of a steam power plant operates at a pressure of 12.35 kPa. Steam at this pressure condenses on the outer surfaces of horizontal tubes through which cooling water circulates. The outer diameter of pipes is 4 cm, and the outer surfaces of the tubes are maintained at 20°C (see the figure). Determine: The rate of heat transfer to the cooling water circulating in the tubes, and The rate of condensation of steam per unit length of a horizontal tube. (45860.1 W, 36.3 kg/h)arrow_forward
- Sample Problem • Four metric tons of pork are to be stored at a temperature of -12°C in 8 hours. The product enters the chiller at a temperature of 21°C and the specific heats above and below freezing are 0.86 kCal/kg-°C and 0.51 kcal/kg-°C, respectively, and its latent heat of fusion is 48 kCal/kg. If the freezing temperature of the product is -5°C, determine the product load in kCal/hr. TCLarrow_forwardThe condenser of a steam power plant operates at a pressure of 0.95 psia. The condenser consists of 144 horizontal tubes arranged in a 12 * 12 square array. Steam condenses on the outer surfaces of the tubes whose inner and outer diameters are 1 in and 1.2 in, respectively. If steam is to be condensed at a rate of 6800 lbm/h and the temperature rise of the cooling water is limited to 8°F, determine (a) the rate of heat transfer from the steam to the cooling water and (b) the average velocity of the cooling water through the tubes.arrow_forwardIndustrial Pipes In very corrosive fluids, can the flow velocities in the pipes be high if the temperatures are low?arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning