Energy recovering using greywater as cold body in a CO2 heat pump water heater.

Paper published in poster form during the conference. The use of heat pumps for the production of domestic water is a fact nowadays. Our research group is involved in a project for the characterization of different configurations of CO2 heat pumps for the production of hot water by recovering the energy contained in the greywater, used this as secondary fluid in the evaporator. This will be done numerically by means of a dynamic study of the different options. As a first step, we have constructed an installation to experimentally analyses these systems and to validate the models we aim to use in the process. So, in this paper, a description of the experimental facility developed is presented. This allows testing four different configurations for the refrigeration circuit which let us to compare their energy efficiency, control capabilities and initial cost and determine what the best solution is. The system is modeled dynamically by using TRNSYS® 17. The data reduction process followed to determine the main operating parameters of the system, as well as a brief description of the uncertainty analysis is presented. The paper finishes presenting a comparison between some preliminary experimental results and the results obtained by using the numerical model developed in TRNSYS® 17.