Reactors for conducting thermochemical processes with solar heat input, and associated systems and methods

A reactor system for processing a reactant, comprising:

• a reactor having a reaction zone;
• a reactant source coupled in fluid communication with the reaction zone of the reactor;
• a solar concentrator having at least one concentrator surface positionable to direct solar energy to a focal area;
• a first actuator coupled to the solar concentrator to move the solar concentrator relative to the sun;
• a radiation control structure positioned between the concentrator surface and the focal area, the radiation control structure having a first surface and a second surface facing away from the first surface, the first surface having a first radiant energy absorptivity and a first radiant energy emissivity, the second surface having a second radiant energy absorptivity less than the first radiant energy absorptivity and a second radiant energy emissivity greater than the first radiant energy emissivity;
• and
• a second actuator coupled to the radiation control structure to change the structure from a first configuration in which the first surface faces toward the concentrator surface, and a second configuration in which the second surface faces toward the concentrator surface.

A reactor system for processing a hydrogen donor, comprising:

• a reactor vessel having a reaction zone;
• a hydrocarbon donor source coupled in fluid communication with the reaction zone of the reactor vessel and carrying a hydrocarbon donor;
• a first product collector coupled to the reaction zone to receive a hydrogen-based fuel produced by dissociating the hydrogen donor at the reaction zone;
• a second product collector coupled to the reaction zone to receive at least one of carbon and a carbon compound produced by dissociating the hydrogen donor;
• a solar concentrator having at least one concentrator surface having a focal area and being positionable to direct solar energy toward the reaction zone;
• an actuator coupled to the solar concentrator to move the solar concentrator relative to the sun;
• and
• a controller operatively coupled to the actuator, the controller being programmed with instructions that, when executed:
• direct the solar concentrator to point toward the sun and focus the solar energy on the reaction zone during daylight hours;
• and
• direct the solar concentrator to point to a location in the sky having relatively little radiation energy to cool an object positioned at the focal area after daylight hours.