Analysis of performance and suitable users of CCHP systems with active thermal energy storage

Introducing a thermal energy storage (TES) unit in the combined cooling, heating, and power (CCHP) system can help alleviate the supply–demand energy mismatch and improve the system performance. However, the active regulation function of TES has not been fully exerted and the applicable user scenarios of the CCHP-TES system are not clear due to the limitations of case studies. In this work, based on the supply–demand energy matching principle, an improved design of active thermal energy storage is proposed to further develop the role of TES units. Meanwhile, to overcome the limitations of case studies and obtain the universal applicable user scenarios, dimensionless user load characteristic parameters are used to analyse the correlation between the user characteristics and the system performances. The system thermodynamic model and integrated design methodology are developed. The results indicate that the average energy-saving rates of the proposed active CCHP-TES system are higher than 14.63%, and the maximum differences compared with those of the conventional CCHP system and passive CCHP-TES system are 22.27 and 29.20 percentage points, respectively. Moreover, among the user load characteristic parameters, the cooling/heating-to-electricity ratio has the greatest impact on the performances of the proposed system, the duration time of the peak electricity load the next, and the peak-to-valley ratio of electricity load the least. In most cases, the larger the cooling/heating-to-electricity ratio and the duration time of the peak electricity load are and the smaller the peak-to-valley ratio of electricity load is, the better the system performance will be. Finally, the applicable user scenarios of the proposed system are given quantitatively and the system is applicable once the peak-to-valley ratio of electricity load is less than 2 and the cooling/heating-to-electricity ratio is greater than 0.5.