Abstract
The northwest of Spain is defined by very high relative humidity values, with an average relative humidity of 85% throughout the year, which is considered too high by most standards and therefore can be related to various health problems and fungi growth. To reduce the relative humidity level in the indoor environment, different dehumidification technologies are being employed. However, commonly employed cooling based dehumidification systems have a very high energy consumption, from 720 W in residential buildings to 3150 W in industrial buildings. This article aims to show a new method for indoor moist air dehumidification, based on a controlled adiabatic expansion of moist air, similar to the Foehn effect, by means of a nozzle–diffuser system. The main results, based on computational fluid dynamics (CFD) simulations and experimental tests in wind tunnels, show an initial working range of up to 80% relative humidity, with almost ten times reduction in energy consumption compared to the classical mechanical refrigeration dehumidifiers. Moreover, future improvements, such as a Peltier cooling system, which allows a reduction of the temperature in the nozzle throat, improving the condensation process, and a variable inlet area, could potentially improve the working range towards the required 30–60% relative humidity in buildings.
Highlights
In accordance with the International Energy Agency (IEA) [1], the energy consumption of buildings is one-third of the final energy consumption globally
A new procedure for moist air dehumidification is shown in the present paper
Initial results showed that a simple nozzle cannot reach an outlet velocity high enough to reduce the pressure and reach moist air condensation
Summary
In accordance with the International Energy Agency (IEA) [1], the energy consumption of buildings is one-third of the final energy consumption globally. ‘Nearly Zero Energy Buildings’ is the latest project of the European Commission [2], whose aim it is to get energy consumption in private and public buildings down to nearly zero by 2020. In this sense, several recent research studies [3,4,5] have described procedures for optimal retrofitting in old buildings, which will go towards helping with low energy consumption. Some of them are centered on passive methods, such as building thermal inertia [6] and phase-change materials, to control moisture in an indoor ambience, and its effects on thermal comfort, with low energy consumption [7]
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