Engineering, 29.01.2020 04:42, zay9357
A25-kg cast-iron wood-burning stove contains 5kg of soft pine wood and 1 kg of air. all the masses are at room temperature, 20 degree c, and pressure, 101 kpa. the wood now burns and heats all the mass uniformly, releasing 1500w. neglect any air flow, changes in mass of wood, and heat losses. find the rate of change of the temperature (dt/dt) and estimate the time it will take to reach a temperature of 75 degree c. assume the iron, wood, as well as air to be incompressible substances (note that this is not a correct assumption, as we will see later in the semester, but it is useful for applying the concepts related to the first law of thermodynamics). c_iron = 0.42 kj/(kg. degree c): c_wood = 1.38 kj/(kg. degree c): c_air = 0.717 kj/(kg. degree c)
Answers: 1
Engineering, 04.07.2019 18:10, siri5645
At 12 noon, the count in a bacteria culture was 400; at 4: 00 pm the count was 1200 let p(t) denote the bacteria cou population growth law. find: (a) an expression for the bacteria count at any time t (b) the bacteria count at 10 am. (c) the time required for the bacteria count to reach 1800.
Answers: 1
Engineering, 04.07.2019 19:10, ndaha
An external consultant recommends that a plant installs a bank of capacitors for power factor correction. this will reduce the peak electrical demand charges by an average of 93 kw every month. the plant current pays $13 per kw in peak demand charges. the capacitor bank will include 223 kw of fixed capacitors, and 183 of variable capacitors. the fixed capacitors cost $59 per kw, and the variable capacitors will cost $65 per kw. the consultant charges 21% of the equipment costs to install the capacitors. because this project will reduce the demand for the electric utility, they are prepared to provide a one-time rebate of $42 per kw of reduced demand. what is the simple payback period for this project (in years)?
Answers: 2
A25-kg cast-iron wood-burning stove contains 5kg of soft pine wood and 1 kg of air. all the masses a...
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