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_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_forwardA 50 gallon water tank/collector is placed on the ground at an angle facing the sun. The tank is 1.5" thick. The average elevation of the sun during solar window is estimated at 60° in this location. a. Determine the optimal angle between the tank and the ground that maximizes the energy reception during the solar window. b. Using the simple model and assuming a 50% energy conversion efficiency, determine the length of the time necessary to raise the temperature of water in the tank from 55 F to 125 E.arrow_forward
- Liquefied 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. answers: a) 375K b) 22.1kWarrow_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 1x106 W. Calculate the surface temperature of the end (facing the sun) of a tank. Calculate the conductive heat transfer through the end (facing the sun)of a tank.arrow_forwardA microwave dinner has the instructions listed below. In this problem, you will explain how following the instructions affect the heat transfer into the meal. (The meal starts off frozen, and is covered with a thin piece of plastic "film" or covering when it is taken out of the box. The vegetables are separate from the beef and potatoes.) Instructions1. Cut slit in film over vegetables.2. Microwave on high 4 minutes3. Turn back film from beef and potatoes. Stir beef and potatoes. Replace film. Return tray to microwave oven4. Microwave on high 3 minutes.5. Let stand 2 minutes in microwave oven., Stir beef and potatoes.a. How does each of the steps above (cut slit in film, stir beef and potatoes, etc) affect the heat transfer to the food? Make sure to consider conduction, convection, and radiation where appropriate. b. The instructions ask you to stir the beef and potatoes, but not the vegetables. From this, what can you tell about how each type of food receives and transfers heat?…arrow_forward
- Calculate the solar angle of incidence on the surface of a south oriented,40 degree inclined PV module at the same time instant located at the same geographical locationarrow_forwardThe surface area of an unclothed person is 1.5m ^2 and thier skin tempature is 33 degree celcius. This ideal person is located in a room with a tempature of 65 dregrees F. and has an emissivity of e=0.95 suppose the room has dimensions 4mx9mx18m a) suppose you and your closest 10 friends come into this room and heat it up. suppose your clothes are in equilibium with your skin and have the same tempature and emissivity. Further suppose that your net power into the room remains constant . How long does it take before the room to get to hot say 95 degreesarrow_forwarda. 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_forward
- The last portion asks you for "net radiant heat flux to the surface", meaning that positive net radiative heat flux means in and negative net radiative heat flux means out. This is opposite the typical sign convention - be aware of thisarrow_forwardRadiators are used in most of the houses’ heating. If we happen to place a sofa justin front of our heating radiator, how will the heating of the room be affected? Explain.arrow_forward5.9 A 200-W c-Si PV module has NOCT = 45°C and a temperature coefficient for rated %3D power of –0.5%/°C. a. At 1-sun of irradiation while the ambient is 25°C, estimate the cell temperature and output power. b. Suppose the module is rigged with a heat exchanger that can cool the module while simultaneously providing solar water heating. How much power would be delivered if the module temperature is now 35°C? What percentage improvement is that? c. Suppose ambient is the same temperature, but now insolation drops to 0.8 kW/m². What percentage improvement in power output would the heat exchanger provide if it still maintains the cell temperature at 35°C? Tamb = 25°C 200-W (DC, STC) NOCT = 45°C PR loss = 0.5%/°C Heat exchanger Cooling water 35°C FIGURE P5.9arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning