Integration of the energy recovery ventilator (ERV) with a traditional HVAC system has gained recent attention because of the potential for energy savings. The energy recovery ventilator selected for this research employs a rotary air-to-air energy wheel with a porous matrix as the heat and moisture transfer medium. The wheel is symmetrical and balanced, operating with counter-flow pattern. The primary goal of this research is to develop a mathematical and numerical model to predict the effectiveness of this energy wheel.
Three models were developed for the energy recovery ventilator (ERV) containing a porous exchange matrix: a sensible model, a condensation model, and an enthalpy model. The sensible model describes the heat transfer in a rotary wheel with a non-desiccant porous matrix. Two energy conservation equations were used to model this ERV. The condensation model describes the heat and mass transfer due to condensation and evaporation in a rotary wheel designed with non-desiccant porous matrix. The enthalpy model describes the heat and mass transfer in a rotary wheel using a desiccant porous media matrix in which adsorption and desorption can take place. Both the condensation and enthalpy models can be mathematically represented by two energy conservation equations with four basic thermodynamic relationships, and two mass conservation equations.
A non-dimensional representation for each model was derived and solved using the finite difference method with the integral-based method formulation scheme. The study examined the effect of wheel design parameters such as: rotational speed, number of transfer units, heat capacity, and porosity of the matrix. Operating parameters such as volume flow rate, inlet air temperatures and humidity ratios were studied, and the numerical results are compared with experimental results. Experimental data of effectiveness obtained from a commercial unit are found to be consistent with the numerical results.