Transcritical CO2 high temperature heat pump for the brewery industry
The brewing industry requires processes at different thermal levels, combining simultaneous heating and cooling demands. A typical process includes wort cooling and water preheating, usually achieved via a heat recovery heat exchanger, along with steam generation for adjunct and mash kettles using a conventional boiler. Water is sourced from the distribution network and pre-cooled in chillers before entering the recuperator to cool the wort to the desired temperature. While part of the steam demand is met using self-produced biogas, additional fuel—typically natural gas—is required. As an alternative for decarbonizing the process, a high-temperature heat pump is proposed to integrate three thermal demands: inlet-water heating, wort cooling, and steam production. The proposed solution is a transcritical CO2 heat pump equipped with a recuperator that divides the gas cooler into two sections: one for heating thermal oil (stored for subsequent steam generation), and another for preheating the inlet water. The heat pump’s evaporator cools the wort, which acts as the thermal source. The inlet water enters the system at 8°C to 24°C and is heated to 90°C. The thermal oil enters the heat pump at temperatures between 136°C and 155°C and returns to storage at 343°C to 269°C. The wort is cooled from 98°C to 10°C, with a thermal load ranging from 9.2 to 18.4 MW??. The seasonal coefficient of performance (COP) for combined heating and cooling is 4.82. The levelized cost of energy (through thermal oil heating) ranges from 67.59 to 78.15 €/MWh??. The payback period varies from 5.31 to 14.7 years, depending on specific economic assumptions.