Eduardo Rubio

Cavity geometry influence on mass flow rate for single and double slope solar stills

Abstract An experimental setup was built in order to evaluate the distillate yield for a double slope laboratory still under controlled conditions for basin water and collector temperatures within typical operating ranges. Additionally, experimental data previously gathered are correlated to propose a new empirical model to estimate mass flow rates in single slope solar stills. This model is compared with those from other published relations and with the double slope still experimental data. It was found that the proposed model reproduces in good agreement shallow stills experimental data and that there is not significant difference in productions between single and double slope cases subject to the same water and cover temperature. Dunkle’s model [R.V. Dunkle, Solar water distillation: the roof type still and a multiple effect diffusion still, International Development in Heat Transfer (Part 5) (1961) 895–902] is found to slightly underestimate production in shallow solar stills.

Effect of passive techniques on interior temperature in small houses in the dry, hot climate of northwestern Mexico

A simple lumped parameter model is used to represent the time variations of internal temperature of a simple house, under hot, extreme weather variation, characteristic of northwestern Mexico. Results are validated by experimental work in a physical model without ventilation, with materials and building techniques typical of low-income family housing in this region. Energy balance in the present work is achieved by means of a system of three simultaneous differential equations, each depicting energy equilibrium in one of the basic building elements: the window glazing, the building materials, and inside air. With the mathematical model properly calibrated, heat transfer coefficients between walls, ceiling and windows are calculated. Passive techniques, such as window shading, orientation and thermal inertia, are evaluated by a normalized temperature index. Results show that interior temperature in the house can be reduced resulting in comfort increase. Then economical pertinence of studied passive elements can be evaluated.

Experimental measurement of the water-to-cover heat transfer coefficient inside shallow solar stills

Abstract The purpose of this work is to measure the overall heat transfer coefficient from water to cover in shallow solar stills using yield measurements. The geometry under analysis represents a real solar still operating with laboratory-controlled temperatures and induced heat flows in steady-state. Temperature differences between the water and the glass cover varied from 2 to 16 K, and water temperature from 298 to 353 K, corresponding to the range of heat flows from 0 to 650 W m−2, in accordance with the operation of a solar still in ambient conditions.

Economic feasibility of passive ambient comfort in Baja California dwellings

The economic evaluation of some passive thermal comfort techniques is performed in order to compare long-term energy savings. A direct comparison is made of vernacular architecture, based on adobe walls, against modern, concrete brick building of low-income family housing in tropical, dry-climate conditions in La Paz, Baja California Sur, Mexico. The expected energy requirements of each type, for the same comfort level, are calculated by means of a calibrated mathematical model, and present value of each option is obtained by conventional means using 10% interest over 15 years. The results indicate that, in cases as those analyzed, the use of vernacular passive techniques is more comfortable and economic than present light buildings by a very wide margin.

Locomotive activity of shrimp in confinement

The activity level of a confined shrimp is evaluated through direct measurement. The developed technique is shown to be several orders of magnitude more sensitive than hot-wire anemometry; it is capable of remotely recording very faint pulses originated from the motion of an organism confined in an aquarium without disturbing the individual.