A parabolic trough is a type of parabolic shaped solar concentrator. The reflective surface is distributed in the parabolic shape of the concentrator, reflecting sunlight on the tubular-shaped receiver located at its focal point where the objects to be heated are placed.
The receiver contains a thermovector fluid (HTF) that can be water, diathermic oil or molten salts, which flows along the channel at its focal line. Sunlight is focused on the tube and the fluid is heated to a high temperature.
This solar energy collector is the most common and commercialized type of parabolic trough collector.
Such a collector is generally aligned on a north-south axis, rotating to follow the sun as it moves from east to west each day.
A concentrating linear Fresnel tracker combines many small mirror fragments to simulate a parabolic cylinder projected onto a plane. These trackers use long, thin mirror segments to focus sunlight onto a receiver located at a common focal point of the mirrors. This concentrated energy is transferred to a thermovector fluid (water, diathermic oil or molten salts).
The mirrors are located at the base of the system and converge the sun’s rays on the receiver. These are usually in a metal structure, generally aligned in a north-south direction, and have a motor that is responsible for moving the mirrors by turning them from east to west, keeping the receiver fixed in its position.
Solar steam for industrial use with storage
Most industrial processes require heat. Existing heating systems for industrial process heat are based on steam or hot water from a boiler, which uses mainly fossil fuels such as oil, natural gas, coal or electricity generated from different sources. Solar process heating systems with thermal storage can supply up to 70% of a plant’s heat demand. This factor depends on the location of the installation and the energy demand profile of the industrial process.
The integration of solar energy with process heat applications requires thermal storage to supply it when it is needed and a strategic control for its discontinuous supply. The design and dimensioning of a solar installation for the production of process steam must take into account the specific demand of the client, and it must be flexible enough to adapt to their needs in real time.
Industrial process heat accounts for almost 75% of the total energy use used in industry.
More than half of the heat demand of industrial processes is below 300ºC, which is a temperature range that a concentrated solar system can perfectly provide. The most promising industrial sectors suitable for this type of solar thermal systems range from alcohol distillation to sugar manufacturing, beverage and food production, the textile sector, as well as tobacco manufacturing, the paper industry, the plastic, the cosmetic sector and many more.