The operating environment is not simply black space, but one with solar radiation and diffuse radiation reflected and emitted from the sun (stars), earth, other objects, and or the spacecraft's own propulsion. It is possible to "orient" the droplet sheet edge towards an external heat source but the sheet area would still be subject to radiation from other sources. Most of the presented solutions of the equation of radiative transfer are practical simplifications by introducing assumptions.
In order to achieve high collection efficiency splashing of the droplet on the collector surface has to be minimized. It was determined that droplet collector with an incidence angle of 35 degrees can prevent a uniform droplet stream with droplet diameter 250 µm and a velocity of 16 m/s from splashing under microgravity condition.
Another solution is to have a liquid film formed on the inner surface of the collector. When the droplet streams are absorbed in this liquid film, no splashes should be formed. A miscapture rate of incoming droplets was required to be less than 10. The droplet diameter was determined to be less than 300 µm and the droplet speed less than 20 m/s.
If a ferrofluid is used a magnetic focusing means can effectively suppress splashing.
As the droplet sheet is in free fall a spacecraft performing a maneuver or angular acceleration would lose coolant. Even a magnetically focused LDR has a very limited tolerance of less than 10 g.
A droplet generator has approximately 10 – 10 holes (orifices) per system with diameters of 50–20 µm.
These orifices are more susceptible to damage than a conventional solid radiator or heat pipe which may affect droplet formation and droplet stream flow direction, potentially causing fluid loss.