PERFORMANCE AND ECONOMIC ASSESSMENT OF A THERMALLY INTEGRATED REVERSIBLE HP/ORC CARNOT BATTERY APPLIED TO DATA CENTERS

Abstract

when the contribution of waste heat occurs, resulting in thermally integrated energy storages. In this context, since data centers (DCs) convert almost all the supplied electricity into recoverable waste heat, this work aims at investigating the convenience of integrating a reversible Organic Rankine Cycle (ORC)/Heat Pump (HP) Carnot battery with a DC fed by a photovoltaic power plant. For this purpose, a detailed semi-empirical off-design model of a CB is implemented in a rule-based control strategy to manage the ORC/HP operations in the integrated system. In case of renewable production surplus, the exceeding energy can be stored in the CB through the HP, which is thermally integrated with DC waste heat with the double advantage of operating with a higher coefficient of performance and of reducing the required cooling system power. The stored energy is reconverted through the ORC when the electric demand overcomes the renewable production. A sensitivity analysis varying the storage volume and the energy price has been performed to investigate the influence of such parameters on the integrated system performance. The thermal integration allows to reach roundtrip efficiencies around 37 %, although the very low operating temperatures. The CB intervention results to be economically convenient, especially when the average electricity price is high as it occurred during year 2022. The yearly additional gain, with a storage volume of 10 m3, is assessed to be around 8270 €, and the simple payback period is less than 10 years