Rankine cycle is a practical cycle of turbine and steam engine. Carnot cycle uses air as the working substance. The Rankine cycle system consists of a pump, boiler, turbine, and condenser. The pump delivers liquid water to the boiler. The boiler heated by the solar heat converts water to superheated steam. This steam is used to run the turbine which powers the generator. The key difference between Rankine cycle and Brayton cycle is that the Rankine cycle is a vapour cycle, whereas the Brayton cycle is a cycle between liquid and vapour phases.
Both the Rankine cycle and Brayton cycle are thermodynamic cycles. The present paper focuses on the comparative experimental operating characteristics of working fluid pumps used in the organic Rankine cycle ORC system with Rfa, including multistage centrifugal pump, hydraulic diaphragm metering pump, and roto-jet pump.
The Rankine cycle or Rankine Vapor Cycle is the process widely used by power plants such as coal-fired power plants or nuclear reactors. In this mechanism, a fuel is used to produce heat within a boiler, converting water into steam which then expands through a turbine producing useful work. An ideal thermodynamic cycle consisting of heat addition at constant pressure, isentropic expansion, heat rejection at constant pressure, and isentropic compression; used as an ideal standard for the performance of heat-engine and heat-pump installations operating with a condensable vapor as the working fluid, such as ….
Rankine cycle is a heat engine comprised of four internally reversible processes. For the two isobaric heat exchange processes, the devices are passive and there is no work, only heat transfer. The ideal Brayton cycle is made up of four internally reversible processes. As what they said above, carnot engine has to be perfectly reversible. We know the second law of thermodynamics, "The entropy of an isolated subject always increases. Edit: If are asking why people need to study carnot engine impossible , it's because it serves as a basic background of all the engines.
Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Why can't we make Carnot heat engine in real life? Ask Question. Asked 5 years ago. Active 9 months ago. Viewed 8k times. Improve this question. Ruslan Add a comment. Active Oldest Votes. In practice neither of these things are possible so you will only ever get "close".
Improve this answer. Floris Floris k 12 12 gold badges silver badges bronze badges. Since the driving force for heat transfer is a temperature difference, this necessarily requires an infinitesimal temperature difference between the heat source and the heat sink, with a consequent infinite amount of time for the heat transfer to occur.
An engine that takes an infinite amount of time to do its job is obviously useless in the real world. Does it look OK to you? It does get worse than that simplified explanation.
Eric Eric 11 2 2 bronze badges. Vasilis Vasilis Vasilis Vasilis 1. Visualize a sealed piston chamber where you: Open an insulating curtain letting heat in while expanding the gas. Closing the curtain and expanding it some more. Opening a second insulating curtain to let heat out, while compressing the gas.
As the difference in temperatures of the hot and cold reservoir increases, the efficiency of a Carnot engine increases. A Carnot Heat Pump Imagine a Carnot heat pump operates between an outside temperature of and an inside temperature of.
What is the work needed if the heat delivered to the inside of the house is Strategy Because the heat pump is assumed to be a Carnot pump, its performance coefficient is given by Thus, we can find the work W from the heat delivered.
Significance We note that this work depends not only on the heat delivered to the house but also on the temperatures outside and inside. The dependence on the temperature outside makes them impractical to use in areas where the temperature is much colder outside than room temperature.
In terms of energy costs, the heat pump is a very economical means for heating buildings Figure. Contrast this method with turning electrical energy directly into heat with resistive heating elements. In this case, one unit of electrical energy furnishes at most only one unit of heat.
Unfortunately, heat pumps have problems that do limit their usefulness. They are quite expensive to purchase compared to resistive heating elements, and, as the performance coefficient for a Carnot heat pump shows, they become less effective as the outside temperature decreases. In fact, below about , the heat they furnish is less than the energy used to operate them.
Check Your Understanding A Carnot engine operates between reservoirs at and. Check Your Understanding A Carnot refrigerator operates between two heat reservoirs whose temperatures are and.
To increase the efficiency of a Carnot engine, should the temperature of the hot reservoir be raised or lowered? What about the cold reservoir? In order to increase the efficiency, the temperature of the hot reservoir should be raised, and the cold reservoir should be lowered as much as possible.
This can be seen in Figure. How could you design a Carnot engine with efficiency? The temperature of the cold and hot reservoirs between which a Carnot refrigerator operates are and , respectively. Which is its coefficient of performance?
Suppose a Carnot refrigerator operates between Calculate the amount of work required to extract 1. A Carnot engine operates between reservoirs at and K. If the engine absorbs J per cycle at the hot reservoir, what is its work output per cycle? A W motor operates a Carnot refrigerator between and. A Carnot heat pump operates between and. How much heat is exhausted into the interior of a house for every 1. An engine operating between heat reservoirs at and extracts J per cycle from the hot reservoir.
Suppose a Carnot engine can be operated between two reservoirs as either a heat engine or a refrigerator. How is the coefficient of performance of the refrigerator related to the efficiency of the heat engine? A Carnot engine is used to measure the temperature of a heat reservoir. The engine operates between the heat reservoir and a reservoir consisting of water at its triple point.
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