RU2657630C1 - Space crafts life support system based on solar bio-panels - Google Patents

Abstract

FIELD: astronautics.

SUBSTANCE: invention relates to biological reactors for the photosynthetic microalgae cultivation, which can serve as a spacecraft (SC) life support system (LSS) element. Flow photo-reactor has a large-area plane-parallel walls and a small gap between the walls and a concentrated algal suspension. Photo-reactor is made in the form of bio-panels (in particular, in the form of a disc or "bellows") and is placed outside the SC sealed volume. This saves space inside the SC and simultaneously solves the problem of the bio-panels (located at an angle to the incident light) illumination by the Sun. Aqueous suspension is separated from the gaseous medium by gas exchange membranes (in particular, in the form of capillaries) or by the action of centrifugal forces during the (disk) photo-reactor rotation.

EFFECT: technical result consists in the creation of an efficient, lightweight and compact algal photo-reactor for SC LSS (it is expected that bio-panels with an area of about 2 m² and a weight of about 5 kg will be able to supply with oxygen and water a SC crew of two persons).

1 cl, 5 dwg

Description

The invention relates to devices - biological reactors for the cultivation of photosynthetic microalgae. Such biological photoreactors can be considered as an element of the life support system (LSS) of a spacecraft (SC).

It is known that the existing life support systems of inhabited spacecraft in near-earth orbits are partially closed and are based both on the reserves of basic substances (oxygen and water) and on their regeneration. The replenishment of the main substances is carried out periodically by cargo ships, which, of course, is not very convenient. And when flying to other planets, you will have to take a large amount of canned food, water and oxygen. For a three-year expedition to Mars, the amount of these non-renewable reserves for a crew of six will be about 30 tons (“The Moon is a step towards the development of the Solar System.” M .: RSC Energia, 2011, p. 316).

The proposed maximally closed LSSs based on physicochemical regeneration processes are very complex, which is bad in itself for a possible emergency breakdown. So, the regeneration system proposed by the Institute of Biomedical Problems (IMBP) consists of 14 blocks, and the extracted carbon dioxide is removed overboard or into the greenhouse (Klimarev S.I., Sinyak Yu.E., Gavrilov L.I. Regeneration crew life support system spacecraft. / RF Patent RU 2500590 C1). And in itself, it is not capable of producing food.

At the initiative of Korolev S.P. Since 1962, a huge number of experiments have been conducted in the USSR to create a closed-type coolant system based on algal photoreactors. In experiments of the Institute of Biophysics and IBMP, it was proved that algae can successfully regenerate oxygen and water in closed pressurized cabins, and potentially produce food. Already in 1966, a high-intensity direct-flow photoreactor with plane-parallel walls was constructed at the Institute of Plant Physiology, which showed the possibility of oxygen regeneration using an aqueous suspension of chlorella. At a culture concentration of 6 * 10 ⁸ cells / ml and a suspension thickness of 5 mm at an illuminance of 800 watts / m ^{2, the} reactor absorbed carbon dioxide with an intensity of 80 l / day * m ² with a modest efficiency of photosynthesis of 5% (Jerusalem N.D., Kovrov B .G. (Ed.) Guided Biosynthesis. M.: “Science” 1966, p. 82). To supply the crew of two people with oxygen, such a reactor would have a mass of 80-100 kg and an area of 15 m ² . Which is comparable with the dimensions of the solar panels of Soyuz TM ships.

We can highlight the disadvantages of algal photoreactors as a possible element of the SCL of the spacecraft.

1. They are, of course, bulky and with any design will occupy a lot of space in the working compartment. The photoreactor with plane-parallel walls has large dimensions. With a high concentration of suspension of 10 ⁹ cells / ml, its optimal thickness of the algal suspension will be 0.25 mm . The need to use thin layers is associated with strong absorption of light in suspension (Lisovsky G.M. (ed.) Guided cultivation of microalgae. M.: “Science” 1964, p. 13). At the same time, the efficiency of photosynthesis in the photoreactor increases 3-4 times, but the area of the photoreactor itself also increases (Lisovsky G.M. (ed.) Guided cultivation of microalgae. M.: Nauka 1964, p. 82).

2. Another disadvantage of the studied photoreactors is that in order to obtain greater productivity, the researchers were forced to irradiate highly concentrated chlorella suspensions with high-intensity light: 400-800 watts / m ² . This reduces the efficiency of photosynthesis, the maximum of which is 15-20%, achieved when the illumination intensity is in the range of 50-150 watts / m ² (Rozhnov VF Space life support systems. M.: MAI, p. 143) Reducing light to the optimum level can increase the efficiency of photosynthesis to 20%, and the efficiency of a photoreactor with a thin layer of algal suspension is 15-20 times (Vladimirova MG, Semenenko V.E., Nichiporovich A.A. Comparative study of the productivity of various forms of unicellular algae, p. 314-326. In the book "Problems of Space Biology" edited by N. M. Sissakian and V.I. Yazdovsky, Academy of Sciences of the USSR, Moscow). At high illumination, the tendency of the suspension to form lumps that settle on the surface of the reactor also increases. The problem of "excess light" is usually solved by the distribution (scattering) of intense light inside the algal suspension using wedge-shaped optical fibers (Tsoglin L.N., Pronina N.A. Biotechnology of microalgae. M .: "Scientific World", 2012. P. 143).

3. Undoubtedly, having a light source for an algal photoreactor on board a spacecraft is an additional technical problem. Moreover, the efficiency of converting electricity to light usually does not exceed 30%. This entails an increased consumption of scarce electricity, the release of heat in the photoreactor, which somehow needs to be removed to the cosmos.

The problem to which the present invention is directed is to design a lightweight and efficient algal flat photoreactor, which, as an element of the SCF KA, forms its external biopanel and would be free from the above disadvantages. It is understood that the biopanel may also include some devices for servicing the photoreactor. For example, for temperature control.

The problem is solved by the fact that

1. For photosynthesis, a flow-through photoreactor with plane-parallel walls and with the maximum possible density of a suspension of algae and the minimum thickness of the suspension itself is taken . This ensures the most complete penetration of light into the suspension, and the high density of the suspension provides greater productivity of the photoreactor. The separation of gases in zero gravity from the algal suspension 1 is achieved by introducing into the reactor with a transparent window 2 a silicone membrane 3 with high gas permeability (Fig. 1, Fig. 2). The cleaned air 4 passes over the membrane 3 , returning carbon dioxide 6 to the suspension 1 . You can also rotate the disk-shaped reactor along with suspension 1 (Fig. 3). The cleaned air 4 is supplied through openings on the periphery of its circumference (not shown in the figure). Enriched with oxygen, air 5 is displaced to the center of the reactor under the action of centrifugal forces. Excess suspension is discharged through a drain hole 7 , and oxygen-enriched air 5 is removed through a gas outlet 8 .

2. In working condition, the photoreactor 9 itself is located outside the KA 10 pressure chamber, thus forming the external KA 2 bio-panel (Fig. 4). This solves the saving of the working volume of the spacecraft, and at the same time the problem of the light source, since its illumination will occur directly from the sun, which eliminates the need to convert sunlight into electricity and electricity back into light to illuminate the photoreactor. In the idle state (at the launch of the spacecraft), the thin bio-panel is in the folded state and takes up little space. Exhaust air, water for regeneration, carbon dioxide and nutrients are supplied to the photoreactor through hermetic joints, by which the biopanel is attached to the spacecraft body. Air enriched with oxygen, purified water and excess algae suspension (biomass) are removed back to the pressurized cabin for further processing and consumption;

3. due to the fact that the solar constant in near-Earth space (1400 watts / m ² ) is an order of magnitude greater than the light intensity for maximum photosynthesis efficiency (about 140 watts / m ² for chlorella), the photoreactor-biopanel 2 (Fig. 4) or the walls of the photoreactor in biopanel 2 (Fig. 5) are located at an angle to the incident light 11 . In this case, the excess light incident on the surface of the biopanel is scattered in the thickness of the suspension, and its light intensity decreases.

According to preliminary calculations, to provide a crew of two people with oxygen and water, a flat photoreactor with a 0.25 mm thick algal suspension of chlorella will have a mass of 5 kg and a total area of 20 m ² . To reduce the intensity of illumination, as described previously, it can be made in the form of an accordion (Fig. 5), which provides a small area of the actual external biopanel: 2 m ² . When selecting suitable algae, as well as aquatic micro-animals that can feed on them, it is possible to obtain a fully enclosed SCF SC. This will save the spacecraft crews from the external supply of food, water and oxygen in low Earth orbit and will allow in the future to make long interplanetary flights to Mars and Jupiter.

Claims (1)

A flowing algal photoreactor with plane parallel walls, containing a suspension of algae with the maximum possible density and minimum thickness of the suspension, characterized in that it is located outside the inhabited pressurized spacecraft and illuminated directly by the Sun, and to reduce the intensity of solar radiation, the plane of the photoreactor or its segments is tilted at an angle to the incident light, while the aqueous suspension is separated from the gaseous medium by gas exchange membranes or by centrifugal force during rotation the photoreactor itself.

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