ON HIGH LEVEL EVALUATION AND COMPARISON OF ORC POWER GENERATORS

asme-orc2015 Tracking Number 25

A review of the thermodynamic performance of ORC’s from public, as well as non-public sources has revealed a correlation suitable to be used as a “rule of thumb” for high-level performance estimation of ORC power generators. Using the correlation, the limited amount of available test data can be generalised leading to a high level evaluation of the commercial benefits of any potential application for ORC’s. Power generators using ORC-technology exist in relatively low numbers. Furthermore, field installations seldom imply comparable boundary conditions. As ORC’s generally operate at low temperature differences between source and sink it has been shown that their relative sensitivity to variations in temperatures i.e. the finiteness of source- and sink, is larger than the sensitivity of power generators operating with large temperature differences. Therefore the establishing of practical “rule of thumb” performance estimation, similar to the term of merit Coefficient Of Performance, COP, as used in refrigeration and air conditioning industry, has previously not been successful. In order to arrange field data in a manner suitable for comparison a refinement of suitable terms of merit was required. The suggested, refined terms are presented and explained as well as critically evaluated against the most common efficiency terms traditionally used. The current lack of a performance “Rule of thumb” leaves room for less serious vendors and laymen to make performance claims unrealistic to practical achievements. Scrutinizing such questionable statements requires detail process simulations and a multitude of technical assumptions. Hence argumentation becomes ineffective. If a suitable “rule of thumb” can be established argumentation against dubious claims would become significantly more forceful. This paper suggests a new term to be used as “rule of thumb” and explains a method on how to use it.