Low-temperature Solar System Research Articles

The Bioburden and Ionic Composition of Hypersaline Lake Ices: Novel Habitats on Earth and Their Astrobiological Implications.

We present thermophysical, biological, and chemical observations of ice and brine samples from five compositionally diverse hypersaline lakes in British Columbia's interior plateau. Possessing a spectrum of magnesium, sodium, sulfate, carbonate, and chloride salts, these low-temperature high-salinity lakes are analogs for planetary ice-brine environments, including the ice shells of Europa and Enceladus and ice-brine systems on Mars. As such, understanding the thermodynamics and biogeochemistry of these systems can provide insights into the evolution, habitability, and detectability of high-priority astrobiology targets. We show that biomass is typically concentrated in a layer near the base of the ice cover, but that chemical and biological impurities are present throughout the ice. Coupling bioburden, ionic concentration, and seasonal temperature measurements, we demonstrate that impurity entrainment in the ice is directly correlated to ice formation rate and parent fluid composition. We highlight unique phenomena, including brine supercooling, salt hydrate precipitation, and internal brine layers in the ice cover, important processes to be considered for planetary ice-brine environments. These systems can be leveraged to constrain the distribution, longevity, and habitability of low-temperature solar system brines-relevant to interpreting spacecraft data and planning future missions in the lens of both planetary exploration and planetary protection.

Optimized low pressure solar DEC with zeolite based adsorption

This paper presents a new concept of hybrid/natural air conditioning system with a high level of architectural integration. A solar DEC (Desiccant Evaporative Cooling) open cycle with very low pressure drops, drastically reduces the electricity consumption for driving fans. The supply air is dehumidified by an innovative zeolite coated adsorption bed and cooled indirectly by an evaporative cooler, through a low pressure drop heat exchanger. The adsorption bed is a finned coil heat exchanger coated with a SAPO-34 zeolite layer realizing both heat and mass transfer in one component. Low thermal grade heat is used to regenerate the adsorbent material, showing high compatibility with low temperature solar systems such as flat plate or evacuated tubes solar collectors. Experimental data have been used for validating a CFD model of the coated coil. The possibility to remove the adsorption heat during dehumidification reduces the air temperature with a positive effect on cooling power.

A Numerical Study on Heat Transfer of High Efficient Solar Flat-Plate Collectors with Energy Storage

The integrated solar collector is considered to be a promising direction for increasing the economic feasibility of low-temperature solar systems for heating water in domestic and industrial applications. Phase change material (paraffin) energy storage can be used in solar water heaters. The paraffin-integrated solar collector eliminates the need of conventional storage tanks, thus reducing cost and space. But a negative aspect of paraffin is that the materials suffer from inherent low thermal conductivity. In this paper, new aluminum foams filled with paraffin were presented to solve this problem. Local thermal equilibrium between the solid filler and the matrix is not ensured in such systems since their thermal diffusivities are very different. A two-temperature model was used for the aluminum frame and liquid paraffin respectively in this paper. A general momentum equation, which includes the Brinkman–Forchheimer extension to Darcy flow, was employed when the paraffin was melted. Apparent heat capacity method was used to simulate the phase change heat transfer of the paraffin melting process in the aluminum foams. The results indicated that the heat transfer ability is significantly improved by using paraffin with aluminum foams and the temperature difference between the frame and liquid paraffin cannot be ignored during the melting/solidifying process.