Annual Performance of Sensible and Total Heat Recovery in Ventilation Systems: Humidity Control Constraints for European Climates

Abstract

Ensuring a comfortable indoor air quality requires a minimum fresh air supply by ventilation. Moreover, the improvement of the air tightness in new and refurbished high performance buildings enhances the role of mechanical ventilation and its importance in further increasing the energy efficiency. Indeed, a reduction of the ventilation load can be achieved by installing air-to-air heat recovery devices, whose potential energy savings can be easily assessed by means of their nominal effectiveness. However, this estimation does not consider the impact on the overall performance of the system, in particular when humidity control is needed. Proper control strategies can be defined on the basis of the indoor latent load to prevent preheating or avoid moisture recovery when dehumidification by cooling is then required. In this work, the energy saving potential of heat recovery systems has been analyzed, considering the impact of different control strategies on both energy and cost savings. The calculations have been generalized using the specific latent load, which allows for the analysis of strategies and savings based on typical utilization categories, without considering in detail all the building characteristics. Representative hourly weather data for 66 European cities have been used to evaluate sensible and total heat recovery devices. The energy and the cost saving results have been mapped per each European Köppen-Geiger climate class and each country, respectively. The proposed strategies based on humidity control can strongly reduce the attractiveness of total heat recovery with respect to sensible heat recovery in terms of energy and cost savings, especially when high specific latent loads are considered.

Eco-friendly Pressure Drop Dehumidifier: An Experimental and Numerical Analysis

“…The main results obtained in the inlet and outlet nozzle zones during the sampling process in the open loop wind tunnel are reflected in Table 1 and in the CFD simulations of the third test shown in Figure 7. The inlet conditions-consistent with previous research works about this validation procedure [27][28][29]-were the same in the real process than in the simulation, as we can see, for instance, in the third test of Table 1 and in Figure 7, in terms of relative humidity (Figure 7a) and velocity (Figure 7b…”

“…Figure 8 shows the maximum velocity value in the nozzle-diffuser throat for an inlet velocity of 5 m/s and relative humidity of 95%. The maximum relative humidity of 100% and its related moist The inlet conditions-consistent with previous research works about this validation procedure [27][28][29]-were the same in the real process than in the simulation, as we can see, for instance, in the third test of Table 1 and in Figure 7, in terms of relative humidity (Figure 7a) and velocity (Figure 7b) distributions, and even in point values in the centre line.…”

Analysis of Ways to Increase Energy Efficiency of Ventilation and Air Conditioning Systems

“…Дослідження показують низьку ефективність їх застосування як в цілях температурної, так і вологої обробки повітря [29].…”

Energy and economic analysis of an auditorium’s air conditioning system with heat recovery in various climatic zones

“…There are also the uncertainties of future energy prices, which may prolong or shorten this period. In a recent research [21] it was concluded that the payback period of a sensible recovery HE, in 24-hour operating ventilation systems, is less than 4 months in Mediterranean countries. Any increase in electricity price by 10% reduces the cost savings rate by 5% in the case of full occupancy and by about 8% in the case of half occupancy.…”