Please let me know if in a generic thermodynamic cycle the thermal regeneration always increase the thermodynamic efficiency of said cycle or not. For example, in the Brayton cycle the thermal regeneration could increase or decrease the thermodynamic efficiency of the cycle in relation to the value of Tmin/Tmax and Pmax/Pmin. So I think that a priori the effect of the thermal regeneration in a generic thermodynamic cycle is unknown, in other word it is necessary to perform evaluation by means of simulations/calculation. Thanks
That totally depends on your definition of efficiency. If you take into account the thermodynamical efficiency thermal regeneration is changing nothing as the efficiency in the thermodynamical sense is regarding to the amount of work that can be done by a thermodynamical system and this is depending on the ratio of T_out and T_in (in the ideal case). However, the only form of work done by a thermodynamical system is volume work (or volume change).
The heat regeneration of such a machine is usually done after the working process of your machine. Hence the thermodynamical efficiency is not influenced by that (unless you regenerate the heat before the system actually does the work - in this case the thermodynamical efficiency goes down as T_in has to be taken after the heat extraction).
If you define the efficiency by how much heat and volume work you can out of your entire system, the answer is: the efficiency is increased as the work is done and the heat from T_out is not just wasted to the surroundings of your machine.
Yes, as Johannes said, it depends on your definition of efficiency.
If you mean efficiency as a ratio of usable work to the heat from the source, in case of ideal cycle (without losses), this efficiency will definetly go up with heat regeneration. In case of real machines, you have to take into account that regeneration process itself is not for free and may take all the benefits of regeration (introducing additional pressure drop, changing Cp/Cv of working media, changing of actual Tin, etc). Also, in case of real machines, the design of regenerated and non-regenerated models can be different so the main working process can be different and cause thermal efficiency change.
So, for ideal cycle the efficiency is always going up, for real cycles it can be different.
decreases, but it is done on practical purposes e.g. to avoid wet compression in a refrig. cycle or to enhance heat transfer in the kettel of a power cycle. So does the mixing and splitting of different streams too.
- Badges
- Science topic
- Similar topics
- Engineering
- Thermal Engineering