International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 13 Issue: 02 | Feb 2026
p-ISSN: 2395-0072
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Surface Wettability Enhancement Strategies for Cast Nylon Plates in Vertical Falling Film Towers: Experimental Implications for Liquid Desiccant Cooling Systems Maheep Kumar Ravi1*, Ankit Goyal1, Priyavrat Kumar1 1Department of Mechanical Engineering, Technocrats Institute of Technology and Science
Anand Nagar, BHEL Opposite Hathaikheda Dam, Bhopal, Madhya Pradesh 462021 ---------------------------------------------------------------------***--------------------------------------------------------------------depletion. In this regard, other cooling technologies that Abstract - Liquid desiccant cooling (LDC) systems have would have the ability to lower the use of electrical energy but still note thermal comfort have received significant research and industrial attention. Of these, one promising option has been liquid desiccant cooling (LDC) systems which so far have found applications where high latent cooling loads are typically present [13].
become an energy-efficient and eco-friendly substitute to traditional vapor compression air conditioning technologies, especially those with high loads in the latent component. The efficiency of the LDC systems is closely related to the efficiency of heat and mass exchange between the liquid desiccant and the process air, which is regulated by the wettability of contact surfaces. Cast nylon plates are also the material that is now being viewed as structured falling film tower packing material because of their low cost, corrosion resistance, mechanical durability, and fabrication ability. Nevertheless, the unruly character of their surface nature, which is largely hydrophobic, does not allow uniform coverage of the liquid films, thus creating dry spots, mal-distributed flows, and diminished system efficiency. This review is a critical analysis of experimental methods that have been used to improve the surface wettability of cast nylon plates in vertical falling film towers that are utilized in liquid desiccant cooling operations. Different methods of surface modification, such as mechanical texturing, chemical treatment, and others, as well as, the use of plasma activation and coating methods are discussed with references to their effects on contact angle, film stability, heat and mass transfer coefficients, and the overall cooling performance. The main experimental results of recent literature are summarized to define the trends of performance, real life challenges, and gaps in the research. The review gives useful information to the researcher and designers who are seeking to maximize the output of the falling film tower by enhancing the wettability control.
Liquid desiccant cooling systems work in the principle of dehumidification with the hygroscopic liquid solutions which may be lithium chloride, lithium bromide, calcium chloride or triethylene glycol. These solutions directly take in moisture in humid air hence decoupling the latent and sensible cooling mechanisms. The separation allows LDC systems to be more efficient and with high indoor air quality than their traditional counterparts [4,5]. LDC systems also have the potential to be recycled with low-grade thermal energy produced by renewable energy sources like solar collectors, geothermal energy, or industrial waste heat, and this makes them even more sustainable [6,7]. Nevertheless, issues of compactness in the system, heat and mass transfer, compatibility with materials and long-term stability in operation remain barriers to the extensive implementation of LDC technology. Out of all the elements of an LDC system, the absorber in which the moisture transfer between air and the liquid desiccant takes place, is one of the primary concerns of the system performance. Vertical falling film towers are frequently used as an absorber because of their capability to offer high interfacial area between liquid and air and at the same time, the construction is fairly easy and the pressure drop is less [8,9]. In such towers, a thin desiccant film of liquid trickles downwards over structured or flat surfaces by gravity, with humid air flowing either in the same direction or the opposite. The excellent heat and mass transfer in this kind of configurations is highly reliant on the establishment of a continuous, stable, uniformly spread liquid film [10]. Any motion that interrupts the flow of the film, e.g. formation of rivulets, dry areas, etc., may greatly decrease the effective contact area, and, therefore, the rate of moisture uptake.
Keywords: Liquid desiccant cooling; Vertical falling film tower; Surface wettability; Cast nylon plates
1. Introduction Over the last twenty years, the demand of energy-saving low-emission cooling technologies in the world has grown significantly because of the high rates of urbanization, the improvement of living standards, and the inevitable apprehension of the climate change. Although the most commonly used, conventional vapor compression airconditioning (VCAC) systems consume a lot of energy and are highly reliant on fossil fuel-produced electricity. In addition, refrigerants that are also used in VCAC systems are also major contributors of global warming and ozone
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