Solar pond powered liquid desiccant evaporative cooling

Abstract

Liquid desiccant cooling systems (LDCS) are energy efficient means of providing cooling, especially when powered by low-grade thermal sources. In this paper, the underlying principles of operation of desiccant cooling systems are examined, and the main components (dehumidifier, evaporative cooler and regenerator) of the LDCS are reviewed. The evaporative cooler can take the form of direct, indirect or semi-indirect. Relative to the direct type, the indirect type is generally less effective. Nonetheless, a certain variant of the indirect type -namely dew-point evaporative cooler -is found to be the most effective amongst all. The dehumidifier and the regenerator can be of the same type of equipment: packed tower and falling film are popular choices, especially when fitted with an internal heat exchanger. The energy requirement of the regenerator can be supplied from solar thermal collectors, of which a solar pond is an interesting option especially when a large scale or storage capability is desired.

The “All in One” Smart Solar Cooling System

“…However, the moisture impregnated desiccants need to be dried in a regenerator, in which the water vapour previously absorbed evaporated out from it by heating. The heat required to regenerate the desiccant can be supplied from low-temperature sources such as waste heat or solar energy [11][12][13]. Utilising solar energy for this application is particularly interesting because the greatest demand for cooling occurs during times of highest solar insolation.…”

“…The characteristics of the desiccant material being utilised impact the performance of the desiccant air conditioning systems significantly [14]. The equipment used for the different components of a desiccant system is air-contacting equipment for liquid air interactions designed for enhanced heat and mass transfer for handling the low liquid flow and large process air flow rates, with minimal air pressure drop, while providing the desired large contact surface area [11,13,15].…”

Solar Pond Driven Air Conditioning Using Seawater Bitterns and MgCl2 as the Desiccant Source

“…With a great amount of progress focussed on the analysis of the efficiency, performance and adverse effect mitigation, the salt gradient solar pond has been shown by many accounts to be a very promising technology for energy storage that can be adapted to many climates and geographical locations. Elsarrag et al [15] reviewed the possibility of supplying the necessary energy required for the regeneration stage of a liquid desiccant cooling system using a salt gradient solar pond. The authors considered different solar pond system configurations, designs and solute materials which would be suitable for implementations in a potential solarpowered desiccant cooling system.…”

QGreen Low-Carbon Technology: Cooling Greenhouses and Barns Using Geothermal Energy and Seawater Bittern Desiccant

“…Several researchers addressed the possibility of using desiccant dehumidification and solar energy [20][21][22][23][24] in conjunction with evaporative cooling systems to be more adaptive with the humid. Their target is to lower the average daily maximum greenhouse temperatures by about 4-6 C compared with the normal evaporative system.…”