Heat transfer and pressure drop in spacer-filled channels for membrane energy recovery ventilators

This article investigates various support spacers for airflow through membrane-bound channels in energy recovery ventilators (ERVs) to enhance heat and mass transfer. Although liquid flow through membrane-bound channels has been extensively investigated, little work has looked at airflow through these channels. This article presents theoretical pressure drop and heat transfer for an open channel and for simple triangular corrugation (or plain-fin) spacers, which are common in heat exchangers and in some ERVs. It then presents the experimental pressure drop and heat transfer for two new corrugated mesh spacers, with one spacer in three orientations. Results indicate that these can improve heat transfer with little pressure-drop penalty compared to the triangular corrugation spacers. Results also show that unsteady flow occurs in the mesh spacers once a certain flow rate is reached. The optimal spacer depends on the application, which is shown with a cost savings estimate for a hypothetical ERV. Simpler performance metrics that do not require cost estimates can be used to compare two spacers, as long as their limitations are considered.

► We investigated support spacers for membrane energy recovery ventilators (ERVs).
► We calculated and measured heat transfer and pressure drop for several spacers.
► New spacer designs show improved performance over simple spacers common in ERVs.
► Tests showed a transition to unsteady flow for velocity ranges expected in ERVs.
► We evaluated the use of common heat transfer performance metrics for ERV spacers.