Condenser cooling water for a power plant is stored in a cooling pond that is 1000m long by 500m wide. However, because of evaporative losses, it is necessary to periodically add "makeup" water to the pond in order to maintain a suitable water level. Assuming isothermal conditions at
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- 7.43 Liquid sodium is to be heated from 500 K to 600 K by passing it at a flow rate of 5.0 kg/s through a 5-cmID tube whose surface is maintained at 620 K. What length of tube is required?arrow_forwardDetermine the rate of heat loss from the wall of a building resulting from a 16 km/h wind blowing parallel to its surface. The wall is 24 m long and 6 m high, its surface temperature is 27C, and the temperature of the ambient air is 4C.arrow_forward5.7 The average Reynolds number for air passing in turbulent flow over a 2-m-long, flat plate is . Under these conditions, the average Nusselt number was found to be equal to 4150. Determine the average heat transfer coefficient for an oil having thermal properties similar to those in Appendix 2, Table 18, at at the same Reynolds number and flowing over the same plate.arrow_forward
- Air stream at 1 atm flows with a velocity of 2 m/s, in parallel over a 3 m long square flat plate, placed on ground, where there is an unheated starting length of 1 m. The air stream has a temperature of 20 °C and the heated section of the flat plate is maintained at a constant temperature of 80 °C. Determine the local heat transfer coefficient at trailing edge and average convection heat transfer coefficient for the heated section. Also calculate the heat loss by convection. Determine the average friction coefficient and wall shear stress and drag force.arrow_forwardA tube bank consists of 300 tubes at a distance of 6 cm between the centerlines of any two adjacent tubes. Air approaches the tube bank in the normal direction at 20°C and 1 atm with a mean velocity of 6.3 m/s. There are 20 rows in the flow direction with 15 tubes in each row with an average surface temperature of 140°C. For an outer tube diameter of 2 cm, determine the average heat transfer coefficient. Assume the air properties at mean temperature of 70°C and 1 atm. The air properties at the assumed mean temperature of 70°C and 1 atm are k = 0.02881 W/m·K, ρ = 1.028 kg/m3, cp = 1.007 kJ/kg·K, Pr = 0.7177, μ = 2.052 × 10−5 kg/m·s, Prs = Pr@Ts = 140°C = 0.7041. The average heat transfer coefficient of the tube bank is W/m2·°C.arrow_forwardA 15 cm x 15 cm circuit board dissipating 15 W of power uniformly is cooled by air, which approaches the circuit board at 20°C with a velocity of 5 m/s. Disregard any heat transfer from the back surface of the board and evaluate properties of air at 300 K. Assume the flow to be turbulent across the entire length of the board since the electric components will have tripped the boundary layer. (a) Determine the surface temperature of the electronic components at the leading edge of the board, and (b) at the end of the board. (c) Ideally, at what temperature would the properties of air be evaluated at?arrow_forward
- Experiments have been conducted on a metallic cylinder 12.7 mm in diameter and 94 mm long. The cylinder is heated internally by an electrical heater and is subjected to a cross flow of air in a low-speed wind tunnel. Under a specific set of operating conditions for which the upstream air velocity and temperature were maintained at V = 10 m/s and 26.2°C, respectively, the heater power dissipation was measured to be P = 46 W, while the average cylinder surface temperature was determined to be T, = 128.4°C. It is estimated that 15% of the power dissipation is lost through the cumulative effect of surface radiation and conduction through the endpieces. Thermocouple for measuring airstream temperature Pitot tube for determining velocity Wind tunnel Power leads to electrical heater Heated cylinder Insulated endpiece Thermocouple leads 1. Determine the convection heat transfer coefficient from the experimental observations. 2. Compare the experimental result with the convection coefficient…arrow_forwardConsider a bullet piercing through calm air during a short time interval in which the bullet’s speed is nearly constant. Determine if the time-averaged airflow over the bullet during its flight is one-, two-, or three-dimensionalarrow_forwardOil flow in a journal bearing can be treated as parallel flow between two large isothermal plates with one plate moving at a constant velocity of 8 m/s and the other stationary. Consider such a flow with a uniform spacing of 0.7 mm between the plates. The temperatures of the upper and lower plates are 40°C and 15°C, respectively. By simplifying and solving the continuity, momentum, and energy equations, determine (a) the velocity and temperature distributions in the oil, (b) the maximum temperature and where it occurs, and (c) the heat flux from the oil to each plate.arrow_forward
- Q5) Air at -10°C flows over a flat surface at 10°C with a free stream velocity of 80 m/s. The length of the plate is 3.1 m. Determine the location at which the flow turns turbulent. Also determine the local value of convection coefficient assuming that the flow is turbulent although.arrow_forwardLiquid ammonia is transported from a production plant to a processing center via a 0.6-m diameter pipeline at a mass flow rate of 0.15 kg/s. Surface temperature of the pipe is maintained 0°C by using a cooling jacket with ice-cold water. Ammonia enters the pipeline at -17°C and exits at -3°C. Assume the flow is both hydrodynamically and thermally fully developed in the pipe. What is the length of the pipe? 185.7marrow_forwardFor safety reasons, air 15cmx20 cm in contact not allowed circuit board, cold air through a 20cm long 0.2cmx14cm rectangular hole drilled inside will be cooled. From electronic parts mosque heat is transmitted from the thin layer of the card to the channel, where the air entering the channel at 15 ° C is removed. The heat flux on the upper surface of the channel can be regarded as uniform and other Heat transfer from surfaces can be neglected. If the velocity of the air inside the duct does not exceed 600m / min and the surface surface of the duct is fixed at 50 ° C, write on this circuit board. Total calculations of electronic parts to be placed.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning