Water Vapor Adsorption–Desorption Behavior of Surfactant-Coated Starch Particles for Commercial Energy Wheels

Abstract

This study reports on the adsorption (dehumidification)–desorption (humidification) behavior of cetylpyridinium bromide (CPB) coated starch particles (SPs), denoted as SP-CPB, as a potential desiccant material for air-to-air energy exchangers. CPB is a cationic surfactant with antibacterial activity that can be used to modify the surface properties of SPs, especially at variable CPB loading levels (SP-CPB0.5, SP-CPB2.5, and SP-CPB5.0, where the numeric suffix represents the synthetic loading level of CPB in mM). The SP-CPB0.5 sample displayed optimal surface area and pore structure properties that was selected for water sorption isotherm studies at 25 °C. The CPB-coated SPs sample (SP-CPB0.5) showed an improved water vapor uptake capacity compared to unmodified starch (SPs) and other desiccant systems such as high amylose starch (HAS15) and silica gel (SG13). Single-step and cyclic water vapor sorption tests were conducted using a small-scale exchanger coated with SP-CPB0.5. The calculated latent effectiveness values obtained from direct measurements using cyclic tests (65.4 ± 2%) agree closely with the estimated latent effectiveness from single-step tests (64.6 ± 2%) at controlled operating conditions. Compared to HAS15- and SG13-coated exchangers, the SP-CPB0.5-coated exchanger performed much better at controlled operating conditions, along with improved longevity due to the CPB surface coating. The presence of CPB did not attenuate the uptake properties of native SPs. Latent effectiveness of SP-CPB0.5-coated exchanger was enhanced (5–30% higher) over that of the SG13- or HAS15-coated exchangers, according to the wheel angular speed. This study reports on a novel and sustainable SP-CPB0.5 material as a promising desiccant coating with tunable uptake and surface properties with potential utility in air-to-air energy exchangers for ventilation systems.

Comparison of the Moisture Adsorption Properties of Starch Particles and Flax Fiber Coatings for Energy Wheel Applications

“…Despite the differences in molecular-level properties of N 2 and H 2 O (size and dipolar character) adsorptive probes, the N 2 BET results provide estimates of the textural properties of FFs versus SPs. By contrast, results obtained for the water vapor isotherms reveal differences because of its adsorbate size, adhesive interactions, and capillary effects, as evidenced by the contrasting results reported for the SPs . The textural properties of the biodesiccants in the present study are further supported by the single-step change and cyclic test results, according to differences in the rate of adsorption/desorption for FFs versus SPs.…”

Surfactant Surface-Patterned Starch Particles for Adsorption-Based Applications: The Role of Sabatier’s Principle

“…We have demonstrated that controlled surface patterning of starch particles yields composite materials with tunable physicochemical properties that are understood according to Sabatier’s principle on the basis of optimal CPB surface adsorption onto SPs. Such surfactant-modified SPs are envisaged to be suitable for advanced applications that require switchable adsorption properties with improved stability/longevity and functional versatility as sustainable carrier systems and desiccant coatings in energy wheels . Sustainability, eco-efficiency, and cost are guiding the next generation of materials with applications in the environment, biomedicine, and energy. − …”

“…Such surfactant-modified SPs are envisaged to be suitable for advanced applications that require switchable adsorption properties with improved stability/longevity and functional versatility as sustainable carrier systems and desiccant coatings in energy wheels . Sustainability, eco-efficiency, and cost are guiding the next generation of materials with applications in the environment, biomedicine, and energy. − …”

Effectiveness of Fixed-Bed Regenerators for Energy Recovery in Buildings Applications

“…The space heating and cooling of commercial, residential, and industrial buildings are responsible for 30-50% of energy consumption and greenhouse gas emissions in Canada [4] and EU [5]. Space heating, cooling, and ventilation of buildings are the main tasks of Heating, Ventilating, and Air Conditioning (HVAC) systems and account for 60% and 54% of the energy consumption by residential and commercial buildings, respectively [6]. Thus, It is estimated that HVAC systems make up 15-30% of global energy consumption [6].…”

“…Space heating, cooling, and ventilation of buildings are the main tasks of Heating, Ventilating, and Air Conditioning (HVAC) systems and account for 60% and 54% of the energy consumption by residential and commercial buildings, respectively [6]. Thus, It is estimated that HVAC systems make up 15-30% of global energy consumption [6].…”