Paper Conference

Proceedings of eSim 2004: 3th Conference of IBPSA-Canada

     

IMPLEMENTATION OF A MODEL FOR THE REDUCTION OF LATENT CAPACITY OF AN AIR-CONDITIONER AT PART-LOAD CONDITIONS WITH CONTINUOUS FAN OPERATION

Kamel Haddad, Jeff Blake, P. Eng

Abstract: The moisture removal effectiveness of air conditioning systems is significantly degraded by continuously running the indoor distribution fan. Results of experiments documented in the literature show that during the equipment off-cycle, the cooling coil acts as an evaporative cooler, providing sensible cooling at the expense of increased air stream moisture content. The degradation in the latent capacity of the air-conditioner was found to increase with an increase in the equipment off-time. A model to predict the degradation of the performance of the air-conditioner was developed by previous investigators. This model accounts for the conditions of the air entering the coil, thermostat cycling rate, air-conditioner transient performance, and the moisture-retaining characteristics of the cooling coil. This model was not implemented within a building energy simulation program when it was developed. In addition, there has been a lack of information on the potential cumulative effect of the latent capacity degradation of the air-conditioner on comfort and equipment electricity consumption over the whole cooling season for different climates. This paper covers the adaptation and implementation of the previous model as part of the airconditioning model in the building energy analysis program ESPr/HOT3000. The model is then used to study the effect of moisture evaporation from the coil, during compressor off-cycle with continuous fan operation, on the temperature and relative humidity inside a residential building during the cooling season. In addition, the effect of the equipment latent capacity degradation on the electricity consumption of the airconditioner is investigated. The findings of the study confirm the negative impact of over sizing the airconditioner on comfort conditions inside the space.
Pages: 127 - 134
Paper:
esim2004_16