Combined Heating and Power: Control Documentation and Efficiency Measurement

Abstract

The University of Plymouth has an experimental Combined Heating and Power (CHP) plant with a poorly documented bespoke space heating loop (SHL), which has led to the existence of some controls with unknown purposes. This research seeks to produce complete documentation for the CHP through experimental methods. This includes taking visual inspections, Thermocouple (TC) temperature measurements, Transit Time Ultrasonic Flow Meter (TTUF) volumetric flow measurements, and Electronic Control Unit (ECL) temperature measurements. The overall thermal efficiency (ηth) measurement methodology will then be assessed as to whether or not it is a suitable protocol for compliance to EU Boiler Efficiency Directive 92/42EEC, and ISO17025: General requirements for the competence of testing and calibration laboratories. The CHP plant was successfully reverse engineered through experimentation to produce documentation of the controls in the form of a schematic. A labelling system was established creating reference between the actual CHP system, and the schematic. The efficiency of the CHP was determined using three different judgements of what is useful space heating. This was found to have a major contribution to the result. The values of ηth varied from 92.3% to 57.2% for assuming all heating power produce by the CHP is useful, to assuming that heat transfer in distribution is to not useful space. A protocol was established to closer meet the EU Directive, however complete compliance would prove challenging. Some areas of priority were highlighted to adhere closer to ISO17025, with certain calibrations and the tracing of systematic errors helping to closer meet the terms of the standard.