What is Rankine cycle: Definition and 60 Discussions

The Rankine cycle is an idealized thermodynamic cycle describing the process by which certain heat engines, such as steam turbines or reciprocating steam engines, allow mechanical work to be extracted from a fluid as it moves between a heat source and heat sink. The Rankine cycle is named after William John Macquorn Rankine, a Scottish polymath professor at Glasgow University.
Heat energy is supplied to the system via a boiler where the working fluid (typically water) is converted to a high pressure gaseous state (steam) in order to turn a turbine. After passing over the turbine the fluid is allowed to condense back into a liquid state as waste heat energy is rejected before being returned to boiler, completing the cycle. Friction losses throughout the system are often neglected for the purpose of simplifying calculations as such losses are usually much less significant than thermodynamic losses, especially in larger systems.

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  1. Kamuna

    Engineering Regenerative Rankine cycle with one contact feedwater heater

    My question is how do i get : A. required steam generated from the boiler per hour B. extracted steam per hour for feedwater heater C. thermal efficiency of the cycle I can solve the thermal efficiency but A and B is giving me difficulties, i know when solving the extraction of steam needs mass...
  2. J

    I Is this water pumping device using the Rankine cycle?

    A while back a was messing around in the shop, and ended up making this water pump that uses only heat to pump. The two check valves are the only moving parts. Here is a drawing of what it looks like inside. Here is another drawing of what I believe it is doing in its cycle. The system...
  3. Kamuna

    Engineering Understanding Rankine Cycle Pressures: Should P2 Equal P3?

    Is this the right path in solving this problem? Am i finding the correct enthalpies? I am also having difficulty understanding so what I've understood is that in a rankine cycle P2=P3 but here P2 is given and P3 has a given variable which is T=25 C too so should I neglect P2=P3? Heres my...
  4. Kamuna

    Engineering How Does Efficiency Impact Calculations in a Regenerative Rankine Cycle?

    I tried to solve and get the answer but i know this is wrong since i didnt use the efficiencies. If you can help me pls indicate where did you use the given efficiency so that i can learn and understand from it. I am still new to this topic. Thank you In a steam power plant operating on...
  5. Kamuna

    What Are High and Low Turbine Stages in a Regenerative Rankine Cycle?

    In this cycle/ schematics I'm a bit confused what are the high turbine stage low turbine stage. Does high turbine occur in state 2? and low on state 345? I am still having difficulties in determining what state is the high turbine or low turbine stage occur please enlighten me I'm just new...
  6. Kamuna

    Thermodynamics Regenerative Rankine Cycle

    Summary:: regenerative rankine cycle Im a bit troubled by my home activity recently and maybe i could use some help this is the problem : In a steam power plant operating on regenerative Rankine cycle with one contact feedwater heater, steam enters the turbine at 8.0 MPa, 350 C and condensed...
  7. R

    Enthelpy and Isentropic compression/expansion

    In a certain thermodynamics textbook, specific work done by an isentropic compressor/pump in an ideal rankine cycles, is given by the following; Wpump = h2 - h1 Wpump = v(P2 - P1), where v = v1 When I carry out these two calculations between any two states, I get vastly different answers...
  8. M

    How to calculate the electrical power output using the Organic Rankine Cycle?

    Basically this would be a closed loop geothermal system for electrical power generation. The system would consist of 2 Horizontal Wells connected creating a U-shaped closed loop cycle using thermosiphon effect, with constant recirculation. It's not really a conventional geothermal power...
  9. B

    Ammonia Rankine cycle heat engine calculation

    A Rankine Cycle heat engine uses ammonia as a working fluid, turbine entry temperature is 25 Bar at 60 degrees Celsius. The turbine outlet pressure is 4 Bar, the question is: what is the outlet temperature? and if the output power is 6 Gigawatt (6x10^9 watt) what would the mass flow rate of the...
  10. alexmahone

    Textbook containing the Rankine cycle (Thermodynamics)

    I'm taking an online course that covers the Rankine power cycle, that, unfortunately, isn't mentioned in any of my textbooks. Do you guys have a textbook that covers this cycle? Thanks
  11. parazit

    Mass of the fuel consumed at the reactor each year?

    Hi fellows. I am dealing with the following question and any help to solve it will be a huge favor. Let us consider a nuclear power plant which delivers 100 MWe. The plant is based on a Rankine cycle, where the steam exiting the reactor is at 350 C and water exits the condenser at 20 C. The...
  12. TheBigDig

    Efficiency of the Rankine Cycle

    WT, the work done by the turbines, as the difference in enthalpy from point 2 to point 3 WP, the work done by the pumps as the difference in enthalpy from point 4 to point 5 Q as the difference in enthalpy from point 3 to point 4 Taking these I get h5 = -252.3kJ/kg. However, my work ratio is...
  13. H

    Thermal efficiency of the Rankine cycle

    Homework Statement Calculate thermal efficiency of R-C cycle with saturated steam as shown in the picture. Steam has 4,5MPa when entering into HP part of the turbine (VT in the picture) and expansion on HP is finished at 0,3MPa. Moisture is then removed in the separator and steam is overheated...
  14. Rafe Zayed

    Second law efficiency of Rankine cycle

    Can you provide me any source from where I can learn about the overall second law efficiency calculation of a simple Rankine cycle?
  15. E

    Confusion about relation of entropy with temperature.

    Why can sometimes entropy remain constant with increase of temperature and vice versa?Entropy implies transfer of heat and heat must increase with temperature.I am unable to intuitively understand.
  16. physea

    B Analyzing open steady flow systems with SFEE vs. Rankine cycle analysis

    Hello I have a point that I don't understand. In open steady flow systems, we use SFEE, where there's a term W in addition to a term PV, which are different things. When we analyse a cycle like Rankine, we always consider either W or PV, but not both. I also think that W=PdV always. Why that...
  17. Al_Pa_Cone

    Steam and Gas Turbines - The Rankine Cycle

    <<Moved from another forum, thus no template filled out.>> I am having some trouble trying to relate a question given in my distance learning lessons to the equivelent question in my assignment. The assignement question is: 1(a) Superheated steam at a pressure of 40 bar and a temperature of...
  18. MCTachyon

    Rankine Cycle Efficiency Calculation - Superheated Steam at 40 bar and 500°C

    Homework Statement Superheated steam at a pressure of 40 bar and a temperature of 500°C is supplied to the turbine of a Rankine cycle. If the condenser pressure is 0.03 bar. Find the thermal efficiency of the cycle. (Neglect feed pump work). I used steam tables found...
  19. Lei

    How to control turbine in Organic Rankine Cycle system

    I am currently working on turbine design for small scale ORC system to produce power from low-enthalpy heat source. In ORC, turbine inlet pressure and flow rate are controlled by pump, and turbine inlet temperature is determined by evaporator when the flow rate of refrigerant and enthalpy of...
  20. G

    Heat injection and work during Rankine cycle

    I have been researching the Rankine cycle. I know that it consists of two adiabatic and two isobaric processes. However, I'm not entirely sure why we ignore the work done during the isobaric processes (this seems to be the case in the analysis I'm looking at). Is that because the work done there...
  21. Nirmal Jayanth

    Can Rankine cycle achieve Carnot efficiency?

    Will a rankine cycle have efficiency equal to the carnot cycle, if the mean temperature of heat addition in rankine cycle is equal to the source temperature of Carnot cycle, and the mean temperature of heat rejection is equal to the sink temperature of carnot cycle. My understanding is that in...
  22. M

    Which Organic Fluid should I used in organic rankine cycle ?

    I'm trying to make a low temp heat exchanger but feeling difficulty in selecting a type of organic fluid some are very toxic, some are not environment friendly. Is there anyone who could suggest me the working organic fluid but it should not be water.
  23. R

    Thermodynamics rankine cycle problem

    1. Steam is the working in an ideal rankine cycle with super heating . Super heated vapor (state 1) enters the turbine at a temperature of 440 °C. Saturated vapor(state 2) exits the turbine at a pressure of 3.0 bar.2. a) Sketch T-S diagram. b)Determine the thermal efficiency of the ideal...
  24. W

    Need Help Mech. Eng. -- An ideal Rankine cycle

    MODERATOR NOTE: THIS IS A MISPLACED COURSEWORK THREAD, SO NO TEMPLATE WAS USED I need help verifying the correct answers for the following questions. 2. An ideal Rankine cycle is operated with a turbine inlet pressure of 500 psia and an inlet temperature of 600 oF. The steam is...
  25. mattyboson12

    Steam Plant Cycle Performance: Analyzing Efficiency

    I am doing an experiment to determine the performance of a steam plant cycle and analyse it in comparison with the ideal rankine cycle. I have a sketch of the actual and real T-S diagram for the steam plant (See attached) I am unsure what factors cause the change in the shape of the T-S...
  26. M

    Rankine cycle with low pressure condenser

    Hi guys, first post on the physics forum! I am slightly confused by the information provided by the following resource, the website is as follows - http://www.learnthermo.com/T1-tutorial/ch09/lesson-B/pg09.php The point that I do not understand is - "For starters, the quality of the turbine...
  27. y2j

    Any help about ORC (organic Rankine cycle)

    Hi anyone can help me about the converting the rotary vane compressor into an expander to use in small scale organic Rankine cycle (micro combined heat and power)
  28. U

    Rankine Cycle Thermal Output Calculation for 1000 MWe

    Homework Statement The last part of my question reads: Give the equations you would use to determine reactor thermal output if the plant is to produce 1000 MWe. All expressions for work and heat transfer rate should be expressed in terms of the appropriate mass flow rate ratios. Homework...
  29. C

    Thermodynamics - Rankine Cycle Reheating

    Homework Statement A Rankine cycle with reheat uses water as its working fluid. Superheated vapour enters the high-pressure turbine at 10 MPa and 440oC. The steam expands through this high-pressure turbine to 0.7 MPa and is then reheated to 400oC. The steam then expands through the low-pressure...
  30. E

    Organic Rankine Cycle efficiency issue

    hi all. just to give you a background story - i am graduate student at U of Calgary in the ECE department. My colleague, from the Mechanical department did not show up yet, because of which I have to work alone on my project, including the mechanical part at which i am no expert but have some...
  31. I

    Partial Expansion in high pressure Turbine in a Reheat Rankine cycle

    Please help me with this, In Reheat Rankine cycle, we first Expand the steam partially in a high pressure turbine and then reheat it again . How is this partial expansion in high pressure turbine done ? in the sense, what is the procedure followed to have only partial expansion of steam...
  32. A

    Why is a condenser necessary in a thermodynamic Rankine cycle?

    hi guys , I am studying thermodynamic cycles in my thermodynamic course , I have a question about the power cycles like Rankine , in these systems v use superheated steam to produce work from turbine, so y there must be condenser to cool it first and then heat it , y can't v use turbine - boiler...
  33. J

    Actual rankine cycle - Work done by pump

    Hi, In what cases do I neglect the work done by the pump in an actual rankine cycle? I am reading that h5-h4 is negligible but in what circumstances do I accept this. Is this only for ideal rankine cycles? As I understand thermal efficiency is (work out + work in)/Heat in Thanks
  34. S

    ORC Setup in Garage - Advice Needed

    Hey I am new to this forum and I am looking for any pointers about my ORC before I start it up? I made an ORC in my garage with two Swep heat ex-changers, one B35 and one B10 (used but flushed). I have hooked up 3 (used) hot water heaters to the B35, 40 gal each with 4.4 kW elements in them, for...
  35. B

    Estimating The Mass Necessary For A Particular Rankine Cycle

    Calculating the Efficiency of A Rankine Cycle For Various Parameters Homework Statement Calculate the efficiency of a Rankine cycle that is modified from the parameters used in the text in each of the following three ways (one at a time), and comment briefly on the on the results: (a) reduce...
  36. T

    Question regarding rankine cycle

    On what factors does the pressure in condenser of a rankine cycle depend? The lesser the pressure in the condenser, the more expansion work will be done by the steam turbine. And depending on the pressure in the condenser, the temperature of the steam entering the condenser will depend...
  37. S

    Open loop rankine cycle with no condenser

    Hello, I'm working on a small scale parabolic trough concentrator project to generate electricity. This electricity is used for pumping water for irrigation,and I want to use an open loop Rankine cycle with no condenser(if it is applicable),to reduce cost,with the steam exhausting directly...
  38. S

    Open loop rankine cycle with no condenser

    Hello, I'm working on a small scale parabolic trough concentrator project to generate electricity. This electricity is used for pumping water for irrigation,and I want to use an open loop Rankine cycle with no condenser(if it is applicable),to reduce cost,with the steam exhausting directly...
  39. J

    Finding Qdot for a Thermodynamic Rankine Cycle

    Homework Statement Water is the working fluid in a Rankine cycle. Superheated vapor enters the turbine at 10 MPa, 480 °C condenser pressure = 6 kPa ηturbine = 80% ηpump = 70% determine a.) Qdot of the steam generator. b.) ηth c.) Qdot from the condenser to the cooling water. Homework...
  40. F

    Does the Rankine Cycle really need a liquid phase?

    A question about Thermodynamics, if someone would help with that... I understand a steam engine that follows the Rankine cycle has basically 4 steps: (a) heating in a boiler; (b) expansion on a piston or turbine; (c) condensation; (d) pump back into the boiler. For many years I have been...
  41. P

    Help finding plans for a simple rankine cycle

    Hello, I am a complete novice and would like to build a simple closed loop rankine cycle that generate electricy, even if it only enough to power a light bulb. I want to learn more about thermal energy conversion in a hands on way, but I am having trouble finding any simple, easy to follow...
  42. F

    Why does the Rankine cycle require the condensation of water before reheating?

    In a Rankine cycle such as a steam power plant, why does the liquid (water) have be condensed before being reheated first? Isn't the Q just extracted during the condensation stage, wasted into a nearby reservoir, and then re-added in the boiler? Could this water not be fed straight to the...
  43. J

    Work input to a pump in a rankine cycle problem

    If a question asks for the "quantity of work input to the pump" is it acceptable to present the answer as positive. I think so because the direction of energy transfer has been defined in the question itself hence there is no need for a sign on the answer. All that's asked for is the...
  44. D

    Help with Organic Rankine Cycle Project

    Help with Organic Rankine Cycle Project please! Moderator's note: this thread is from May 2011 Hi there everyone, I'm posting here in the hope that someone will be willing to help an engineering layman do some calculations, I'm a plumber not an engineer. Thanks to anyone who decides to help...
  45. K

    Help! Rankine Cycle Turbine: Finding Low Cost Feed Pump Advice

    Hello! first time user, in desperate need of advice: My company (start up) has built a 5 hp Rankine cycle generator with a thermal efficiency of about 33%, it works fantastic in an open cycle, however 6 engineers and many pump specialists later, and i am still at a loss... My system uses...
  46. Q

    Good book for studying rankine cycle

    so what book is the best when dealing with rankine cycle? i hope it has tons of problems with solution manual (for self-study purposes) pls. thanks
  47. A

    Understanding Condensation in a Rankine Cycle

    I am a 2nd year mech engg student. I have a basic doubt in condensers. The steam from turbine exhaust enters the condenser & gets condensed during which its specific volume decreases resulting in formation of partial vacuum. Now according to rankine cycle the process in a condenser is a isobaric...
  48. A

    Rankine Cycle with Reheat+Regen

    Hello, I'm working on designing a rankine cycle steam power plant for a class and am trying to incorporate both reheat and a direct contact feedwater heater for regen. I've attempted to read up on this online but beyond some basic information it's hard to find anything. My question is should I...
  49. A

    Thermodynamics (Ideal Rankine Cycle)

    1. An ideal reheat Rankine cycle operates between the pressure limits of 10 KPa and 8 MPa, with reheat occurring at 4 MPa. The temperature of steam at the inlets of both turbines is 500C, and the enthalpy of steam is 3185 KJ/kg at the exit of the high-pressure turbine, and 2247 KJ/kg at the exit...
  50. L

    Gas cycle, rankine cycle, organic rankine cycle, kalina cycle, and all that

    (maybe it fits better in this forum) Hello, I have been asked an advice about waste heat to power systems (say wh2p). The available waste heat to be considered is a (dirty) gas in a temperature range between 250°C and 450°C. The useful power that could be generated would range between...