Investigation of a solar-driven absorption heat transformer with various collector types for industrial process heating

Abstract

Waste heat recovery and upgrading is an effective measure for facing the energy problems in the industrial sector. This could even be more impactful when combined/boosted with compatible renewable energy systems. The objective of the present work is the comparison of three different collector types coupled to an absorption heat transformer for industrial process heat production. The absorption heat transformer operates with LiBr/water as a working pair and aims to upgrade the heat with a thermochemical process to cover a wide range of different temperature needs in the industrial sector from 80 °C up to 160 °C. The novelty of the present work is based on the systematic investigation and comparison of three different solar thermal collectors innovatively feeding an absorption heat transformer. Simple flat plate collectors, advanced flat plate collectors, and evacuated tube collectors are the investigated solar technologies. The investigation is conducted with a developed model in the Engineering Equation Solver tool. For industrial process heat temperatures from 95 °C up to 120 °C, the simple flat plate collector is the best choice, for greater temperatures up to 140 °C, the advanced flat plate collector is the best solution, and for higher temperatures, the evacuated tube collector outperforms others. For a solar energy input of 80 kW in these cases, the process heat supply at 115 °C by the system using simple flat plate collectors is 11.01 kW, at 130 °C using advanced flat plate collectors is 13.11 kW, and at 150 °C with evacuated tube collectors is 14.12 kW. The respective exergy efficiency values of these systems are 3.43 %, 4.86 %, and 5.60 %, respectively.