Parabolic trough collector. A set of parabolic mirrors can be used to concentrate the sun's rays to heat a fluid flowing in a pipe positioned at the mirrors' focal points (Camacho, 2012). The healed fluid, such as oil. for example, is transported to a pressurized lank to be used to create steam to generate electricity or power an industrial process. Since the solar energy varies with time of day, time of year, cloudiness, humidity, etc., a control system has to be developed in order to maintain the fluid temperature constant. The temperature is mainly controlled by varying the amount of fluid flow through the pipes, but possibly also with a solar tracking
Assuming fixed mirror angles, draw the functional block diagram of a system to maintain the fluid temperature a constant. The desired and actual fluid temperature difference is fed to a controller followed by an amplifier and signal conditioning circuit that varies the speed of a fluid circulating pump. Label the blocks and links of your diagram, indicating all the inputs to the system, including external disturbances such as solar variations, cloudiness. humidity, etc
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Control Systems Engineering
- Describe and compare the modes of heat loss through the single-pane and double-pane window assemblies shown in the sketch below.arrow_forwardA pipe still uses 7110 lb per hour of a cracked gas (Net Heating Value (NHV) 20560 Btu per lb). The radiant section contains 1500 sq ft of projected area, and the tube (5 in. outside diameter) are spaced at a center-to-center distance of 10 in. there is only one row of radiant tubes, and they are 40 ft long. The ratio of air to fuel is (21 (30 percent excess air). a) What percentage of the heat liberation is absorbed in the radiant section? b) How many Btu are absorbed per hour through each square foot of projected area?arrow_forward1. Solar Collector Problem: From the diameter of the sun and the earth and the mean distance of sun from earth, estimate (a) the amount of energy emitted from the sun, (b) the amount of energy received by the earth, and (c) the solar constant for a sun temperature of 5700K. If the distance of Planet-Y from the sun is 7.0 astronomical unit, estimate, (c) the solar constant for Planet-Y for a sun temperature of 5700K. (Stefan-Boltzmann constant, o = 5.67 x 10-8 W/m2-K4). Diameter of the sun = 1,392,000 km; DiaPlanet-y = 340,800 km; Mean distance of the sun from the earth = 149,600,000 km r Sun R 0₂ m Aa ||A₂ Ar Concentratorarrow_forward
- The fuel assembly shown in the left figure consists of periodic arrays of annular bare fuel rods, which are cooled by passing water through the center of the rods as well as over the outer surface. We want to analyze the thermal performance of the fuel rods by dividing the assembly into a number of unit cells (control volumes) and evaluating the performance of a cell, as shown in the right figure.arrow_forwardCalculate the rate of heat transfer by radiation from an unlagged steam pipe, 50 mm, o.d. at 393 K (120° C) to air at 293 K (20° C). Assume emissivity 'e' of 0.9.arrow_forward(a) Find the refrigeration capacity if no insulation is used for the walls and ceiling. (b) Select insulation(s) for the wall and ceiling to reduce the refrigeration capacity. Evaluate the thickness required for the insulation you selected to reduce the refrigeration load by approximately 30%. (c) Add a 1m x 1m window glass to the room. Use the data collected from previous parts. Assume the internal surroundings surfaces (e.g., walls and ceilings) have the same temperature as the inside temperature, and the external surroundings (landscape, buildings, etc.) are also at the same temperature as the outside temperature. Assume the convection coefficients between air (internal and external) and the glass are the same as the walls and the air. If the glass has an emissivity of 0.9, calculate the rate of heat loss through the glass. Assume steady-state conditions, negligible temperature gradients in the glass, and both inner and outer surfaces exposed to large surroundings.arrow_forward
- Solve using the methodology : Known, Find, Schematic Diagram, Assumptions, Properties, Analysis and Comments.arrow_forwardPlease answer the given problem and show the solution. Thank you very much! Note: Please include the unit in the solution and use 4 decimals point in final answer.arrow_forwardheat transfer ,(thanks) The temperature of the outer surface of a vertical tube through which hot water is flowing is 275 K. The temperature of the external environment where the tube is located is 232K. The outer diameter of the tube is 30 mm and the length is 150 mm. Its work simply disappears from the side surfaces of the cylinder.a. Calculate the loss, ignoring the radiation losses.b. Calculate the loss from the pipe with the increase of natural convection(s=0.55 for steel tube)arrow_forward
- a. What does it mean when we say that a surface 'sees itself' in the context of radiative heat transfer? b. If heat transfer by conduction through a medium occurs under steady- state, will the temperature at a particular location vary with time? Will the temperature vary with location in the medium?arrow_forwardNote:- • Do not provide handwritten solution. Maintain accuracy and quality in your answer. Take care of plagiarism. • Answer completely. • You will get up vote for sure.arrow_forwardLiquefied natural gas (LNG) is transported around the globe using ships similar to thatshown in Figure QA3. This ship has four pressurised cylindrical steel tanks each ofradius of 20 m. The tanks are internally insulated with 30 cm of polyurethane foamwhich keeps the LNG at a constant -162 ºC. Take the effective sky temperature is 265K and the net radiative thermal energy exchange with the sky as 1x10^6 W. (a) Calculate the surface temperature of the end (facing the sun) of a tank.(b) Calculate the conductive heat transfer through the end (facing the sun)of a tank. DATA FOR QUESTION: Thermal conductivity, polyurethane foam = 0.02 W/mKStefan’s Constant = 5.67x10^-8 W/m^2K^4Emissivity, steel = 0.95 answers: a) 375K b) 22.1kWarrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning