J.R. Henríquez

Bio: J.R. Henríquez is an academic researcher. The author has contributed to research in topics: Airflow & Heat flux. The author has an hindex of 1, co-authored 1 publications receiving 38 citations.

Simplified model for a ventilated glass window under forced air flow conditions

Abstract: This paper presents a study on a ventilated window composed of two glass sheets separated by a spacing through which air is forced to flow. The proposed model is one dimensional and unsteady based upon global energy balance over the glass sheets and the flowing fluid. The external glass sheet of the cavity is subjected to variable heat flow due to the solar radiation as well as variable external ambient temperature. The exchange of radiation energy (infrared radiation) between the glass sheets is also included in the formulation. Effects of the spacing between the glass sheets, variation of the forced mass flow rate on the total heat gain and the shading coefficients are investigated. The results show that the effect of the increase of the mass flow rate is found to reduce the mean solar heat gain and the shading coefficients while the increase of the fluid entry temperature is found to deteriorate the window thermal performance.

The function of solar absorbing window as water-heating device

Abstract: While window glazing will be more and more extensively used in modern architecture, the increase in space thermal load as a result will deteriorate the global environment, incurring problems of air pollution and climate change. By connecting the cavity of a double pane window to a water-flow circuit, absorbed solar heat at the window glasses can be readily removed by the water stream. The water passage in this way can effectively lower the glass pane temperature, reduce room heat gain and therefore, the air-conditioning electricity consumption. Thermal comfort can be enhanced. Furthermore, the water-flow window can function as a hot-water preheating device. This article reports the integrative thermal performance of a water-flow absorbing window as compared to the conventional single and double pane absorptive glazing. The results based on the operation in health club environment are very encouraging. This demonstrates its good application potential in domestic–commercial buildings with stable hot-water demands.

An experimentally validated mathematical and CFD model of a supply air window: Forced and natural flow

Abstract: Computational Fluid Dynamics (CFD) has been used, with considerable success, in modelling the physics in supply air windows. In this research, a comprehensive three-dimensional CFD model is proposed. Under the conditions investigated, the temperature rise and heat gain ranged from 6 K to 24 K and 23.45 W/m2 to 96.34 W/m2, respectively. The temperature rise and heat gain were higher in the natural flow case than in the forced flow cases. The models were experimentally validated in terms of velocity field, flow field and temperature rise. The velocity field was measured using Laser Doppler Velocimetry (LDV) and the overall flow field was captured using smoke for flow visualisation. Qualitatively, the CFD predictions are in good agreement with experiment. Quantitatively, there is noticeable error between experiment and CFD. The average error between CFD and experiment is: 3.46 K for temperature values at the outlet, 35% for axial velocities in the cavity and 44% for turbulence intensity in the cavity. The results indicate that good agreement could be obtained, between experiment and CFD, if the LDV seeding issues are resolved and a turbulence model that is capable of resolving anisotropic turbulence and transition is used.

Thermal performance of natural airflow window in subtropical and temperate climate zones – A comparative study

Abstract: Airflow window is highly useful in conserving building energy, and lessens the comfort problems caused by glazing. In this study, the thermal performance of a natural airflow window was examined through the use of a dynamic model, developed based on the integrated energy balance and airflow networks. The validity of the model was first tested by measured data obtained from a prototype installed at an environmental chamber. The application in the subtropical and temperate climate zones were then examined with the typical weather data of Hong Kong and Beijing. The findings confirmed that the natural airflow window can achieve substantial energy saving in both cities, and the reversible window frame is only required for Beijing, a location with hot summer and cold winter. The space cooling load via fenestration in Hong Kong, a subtropical city, can be reduced to 60% of the commonly used single absorptive glazing. In Beijing, as an example of the temperate climate, this can be reduced to 75% of the commonly used double glazing configuration in the summer period, and the space heat gain can be improved by 46% in the winter period.

Behaviour of a SPD switchable glazing in an outdoor test cell with heat removal under varying weather conditions

Abstract: Suspended particle device (SPD) switchable glazing has potential to control transmission of solar radiation in the visible range by changing its transparency from 55% to 5%. Outdoor test cell characterisation of a SPD switchable glazing offered the dynamic solar heat gain coefficient (SHGC) which varied between 0.05 (when opaque) and 0.38 (when transparent). Reduction of maximum temperature rise of 11% and 15% was possible using SPD “transparent” and “opaque” state compared to same area double-glazing. Insulated test cell with water flow heat exchanger was employed to measure the cooling load reduction potential of SPD glazing while its transmission changed from “transparent” to “opaque” state. A cooling load reduction up to 6 kW h for a 0.343 m 3 volume test cell was possible by changing a 0.21 m × 0.28 m SPD glazing transparency from “transparent” to “opaque”. Average overall heat transfer coefficient of SPD glazing varied between 5.02 W/m 2 K and 5.2 W/m 2 K for two different states.

Dynamic modeling of the ventilated double skin façade in hot summer and cold winter zone in China

Abstract: An improved zonal approach with a dynamic optical model of the venetian blind and airflow network model is proposed to model the mechanical ventilated double skin facade (DSF) in hot summer and cold winter zone in China. It is validated by the experiment in both cooling and heating season cases. The comparison results show that the simulated results fit well with the measured results. The effects of the ventilation rate and slat angle on the inner glass temperature and heat gains through the DSF are discussed. Both increase ventilation rate and slat angle can decrease the inner glass temperature and heat gains through the DSF, but the decrease range is greater by increasing the slat angle. Compared to the slat angle at 0°, heat gains can be reduced by 63% when the slat angle at 60°. The proposed method can not only meet the requirements of engineering application, but also spend less computational time in modeling DSF dynamically in hot summer and cold winter zone in China. It can be used to evaluate the thermal performance and simulate the annual energy consumption of DSF.