More or less as others have indicated. We can know mass flow rate and temperature in various systems of the plant, so we can determine the temperature (enthalpy drop) through the condenser in the secondary cooling system, or through the steam generator.bizarro186 said:Hello everyone,
I was wondering how one can go about accurately estimating the amount of the waste heat rejected from a PWR and the temperatures of said waste heat. Thank you very much.
Regards,
Jon
bizarro186 said:accurately estimating... the temperatures of said waste heat.
Actually, some of the German PWRs are around 35.7 to 36.4% efficient based on some innovation in turbine design by Siemens.Muti said:... and to add further we can not further utilize this 63~ 68 % energy because temperature rise in condenser water is small. Secondly we can not further increase PWR theoretical efficiency from around 33% because steam it produce is saturated.
bizarro186 said:Hello,
Thank you everyone for your replies. I am a mechanical engineering undergraduate student with little nuclear engineering knowledge. For one of my heat transfer projects, I plan on investigating the amount of useful heat energy that can be recovered from the waste heat rejected from a nuclear reactor, which could then perhaps be used to power an adsorption desalination plant. Unfortunately, I'm not entirely sure how I can go about doing this. Theoretically, how does one calculate the amount of heat energy available from the water in the condensers? Surely it can't just be Qr(Reactor thermal power) - Pe(Electric power output) = Qw(Heat dissipation)?
Thank you once again.
Regards,
Jon
PSAT for TAVG?Hiddencamper said:[ ... ] Not sure what steam generator pressure for PWRs is.
minus the temperature difference across tubes..Doug Huffman said:PSAT for TAVG?
Really? A measurable tube Delta_T?jim hardy said:minus the temperature difference across tubes..
The rejected low temperature heat can not be economically used in more conversion cycles, but it can certainly be used as is, that is for space/water heating in district heating applications. The current remote location of large nuclear plants makes this untenable, but the potential of small modular reactors and their much increased safety margins is that they'll be located close to the load and then allow the waste heat to be used for space heat. I don't know of any better method to eventually decarbonize heating.Muti said:... and to add further we can not further utilize this 63~ 68 % energy because temperature rise in condenser water is small. ...
I believe PWR steam pressure is about 900 to 1000 psi, for modern high duty plants. Alstom's Arabelle 1750 MW turbine for the EPR has a main steam pressure of 75 bar (at 290 C) or 1088 psia. Condenser pressure is 46 mbar.Hiddencamper said:Saturation temperature for steam at 27 inches of mercury vacuum (about 2-3 psia) wouldn't be a bad assumption. Large steam turbines cannot operate at low load with less than 25 inches hg of vacuum, and high load less than 24 inches continuously. Typical vacuum is 27 inches Mercury +/- 1. Again that's just approximate numbers for the couple large bwr units I've seen.
As for mass flow, it's going to be roughly equal to your reactor or steam generator steam output. Most nuclear plants boil their water at saturation conditions, so figure out how many pounds of water it takes to remove 3400 MWth from the core. BWR pressure is in the 950-1050 range. Not sure what steam generator pressure for PWRs is.
Such as the Pius reactor proposed by ABB atom in the 80s.. If it weren't for Chernobyl, one of those would have been built in Helsinki.mheslep said:The rejected low temperature heat can not be economically used in more conversion cycles, but it can certainly be used as is, that is for space/water heating in district heating applications. The current remote location of large nuclear plants makes this untenable, but the potential of small modular reactors and their much increased safety margins is that they'll be located close to the load and then allow the waste heat to be used for space heat. I don't know of any better method to eventually decarbonize heating.
Waste heat rejected from PWRs refers to the excess heat that is produced during the nuclear fission process in Pressurized Water Reactors (PWRs). This heat is generated as a byproduct of the nuclear reactions and needs to be removed from the reactor core to prevent overheating and potential damage to the reactor.
Estimating waste heat rejected from PWRs is important for several reasons. First, it helps in the design and operation of the reactor cooling systems to ensure that the excess heat is effectively removed. Additionally, accurate estimation of waste heat can aid in the overall efficiency and performance of the reactor, as well as in the evaluation of potential environmental impacts.
The estimation of waste heat rejected from PWRs involves complex calculations and modeling based on various factors such as reactor power, coolant flow rate, and reactor design. The most commonly used method is the heat balance method, which takes into account all heat inputs and outputs to the reactor core.
Several factors can affect the amount of waste heat rejected from PWRs. These include the reactor power level, coolant flow rate, reactor design and operational parameters, as well as environmental conditions such as ambient temperature and humidity. Any changes in these factors can impact the overall amount of waste heat rejected from the reactor.
Waste heat rejected from PWRs is typically managed through various cooling systems, such as the primary, secondary, and tertiary cooling systems. These systems use different heat exchange processes to remove the excess heat and dissipate it into the environment. Some PWRs also utilize waste heat for other purposes, such as district heating or desalination.