The steady state performance testing of industrial-scale energy wheels requires large-scale and advanced instrumentation to analyze large volumes of data. In order to address the feasibility of laboratory-scale studies, experimental modelling and data simulation have been successfully performed by means of the transient and cyclic testing of a heat exchanger within an energy wheel setup in a parallel-flow air stream configuration. However, major challenges have been encountered in terms of predicting the effectiveness of a counter-flow energy wheel configuration in different operating conditions via the use of a transient test setup in a parallel-flow configuration. In the present study, we report the modification of a transient test facility intended to facilitate the more accurate simulation of a full-scale energy wheel operation in a small-scale test facility. A new test section was designed to: (1) enable tests in both counter-flow and parallelflow configurations; (2) afford automated cyclic testing and achieve the reliable simulation of the energy wheels dehumidification/regeneration cycles; and (3) enhance the accuracy and reduce the uncertainty of the relative humidity (RH) measurements through utilization of the bag sampling method. The latter method is shown to yield greater accuracy with regard to the RH in non-isothermal operating conditions, as well as to reduce the data processing required for the estimation of latent effectiveness.

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Air-to-air energy recovery ventilators (ERVs) are able to reduce the required energy to condition ventilation air in buildings. Among different types of ERVs, fixed-bed regenerators (FBRs) have a higher ratio of heat transfer area to volume. However, there is limited research on FBRs for HVAC applications. This paper presents preliminary experimental and numerical research of FBRs at the University of Saskatchewan. The numerical and experimental results for effectiveness of FBR agree within experimental uncertainty bounds and the results agree with available empirical correlations in the literature.

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.

The adsorption–desorption behavior of flax fibers (FFs) is reported in this paper. FFs are a potential desiccant material for air-to-air energy wheels, which transfer heat and moisture in building heating, ventilation, and air conditioning (HVAC) systems. The raw FFs sample was subjected to physical modification, followed by complementary material characterization to understand the relationship between its structure and its moisture uptake performance. The surface and textural properties of the modified FFs were determined by gas adsorption (N2, H2O) and gravimetric liquid water swelling studies and further supported by spectroscopic (infrared and scanning electron microscopy) results. A FF-coated small-scale energy exchanger was used to determine the moisture transfer (or latent effectiveness; εl) using single-step and cyclic testing. The FF-coated exchanger had εl values of ∼10 and 40% greater compared to similar exchangers coated with starch particles (SPs) and silica gel (SG) reported in a previous study. The enhanced surface and textural properties, along with the complex compositional structure of FFs and its greater propensity to swell in water, account for the improved performance over SPs. Thus, FFs offer an alternative low-cost, environment-friendly, and sustainable biodesiccant for air-to-air energy wheel applications in buildings. The current study contributes to an improved understanding of the structure–function relationship of biodesiccants for such energy wheel applications.

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