Multi-objective dynamic integration of a solar thermal system in the agro-industry processes: Methodology and case study

Abstract

The agro-industry sector requires a large share of thermal energy for low-temperature applications to comply with the actual sustainability roadmaps and decarbonization targets. Heat demands should be supplied by different energy sources depending on the temperature level. Consequently, there is a huge potential to substitute ordinary fossil fuels energy sources with those from renewable sources. One of the challenges that hinders its application consists of the dynamic operation and the matching between the solar system and the industrial process.

The main objective of this work is to foster solar heating integration in both new and existing industrial and agro-industrial plants.

This work presents a methodology to evaluate the dynamic integration of a solar thermal system applied to a production site of the winemaking industry. Although several research papers have been developed to evaluate the integration between the solar system and the industrial/thermal processes, this work intends to extend the current framework for wider integration. Unlike conventional stationary analysis, this methodology considers the transient behaviour of the solar thermal source. For this purpose, a transient simulation software (TRNSYS) coupled to a Java Application (JEPlus) was used to evaluate different process configurations and requirements. In this way, a combination of schedules, process temperatures, heat demand and storage systems is considered.

The study novelty lies in a transient state solution, which considers the seasonal generation of solar energy and the fluctuations in the production processes. Therefore, this fact implies a high potential for replicability in a wide range of industrial and agro- industrial sectors, solar technologies and geographical locations. A post-processing algorithm was developed in Python to collect and analyse data from the resulting simulations. Finally, multi- optimisation solutions were used to assess the best integration process according to the balance between energy and exergy metrics.