Ingenieria

ANALYTICAL THERMAL MODEL OF SOLAR WATER HEATER FOR SOCIAL HOUSING APPLICATION
R. D. Maldonadoa, A. I. Olivaa,b, E., A. Díazc, A. I. Montalvoc
a Universidad Anáhuac-Mayab, Facultad de Ingeniería. Carretera Mérida-Progreso Km. 15.5, A. P. 96, Cordemex, C. P. 97310, Mérida, Yucatán, México.
Phone +52 (999) 9424800 Ext. 524, Fax: +52 (999) 9424807.
E-mail: ruben.dominguez@anahuac.mx
b Centrode Investigación y de Estudios Avanzados del IPN Unidad Mérida. Depto. de Física Aplicada Km. 6 Antigua Carretera a Progreso, A.P.73-Cordemex, C. P. 97310, Mérida Yucatán México. Phone +52 (999) 91-242136, Fax: +52 (999) 9812917.
E-mail: oliva@mda.cinvestav.mx
c DM Energía Verde S.A. de C.V., Calle 32B No. 402, Chuburna Inn., C. P. 97205 Mérida, Yucatán, México. Phone: +52 (999) 2863194.E-mail: diazenergia@hotmail.com
Abstract
The sun has been a constant source of free-energy through the humanity evolution. Today, it is used for different activities, such as agriculture, and social and industrial activities. For a better use of this inexhaustible source of energy, is necessary to develop new technologies for its reception, transformation and application. This work aims to proposean analytical thermal model to optimize data to produce a solar water heater device to be included in social homes as an echo-technology. The analytical thermal model is based on an energy balance, which takes into account the different heat transfer mechanisms (conduction, convection and radiation) involved in the components. Experimental values of reflectance and absorbance values ​​of the usedmaterials in the solar water heating device are included in the proposed model in order to simulate real conditions to be included in the final prototype. A detailed thermal model for optimizing the better materials-type, geometry and number of tubes, coating-absorption materials, among others, are discussed. Results of the analytical thermal model give us the optimum parameters to be used in thesolar water heater device for social homes with regional adaptability. Present work represents an effort developed by the teamwork integrated by DM Energía Verde Company, Universidad Anáhuac-Mayab and Cinvestav-Mérida for social housing problems in the Peninsula of Yucatán.

1. Introduction
Solar collectors are essential equipment which transforms the solar radiant energy to useful energyform to a fluid. Heat water using the sun's energy is an activity that has taken place since the ancient Greeks. However, to achieve effectiveness, it refers to the form or mechanisms used to capture and trap the sun’s energy and try to maximize their energy radiated per unit area of capture. A solar water heater uses the sun's heat energy to increase its temperature as it passes through a ductcausing a heat exchange. To collect the heat can be used different techniques to capture energy. Ideally, the heat trapped by the fluid is used in the same proportion that comes from the source. However, this is not possible under the optical properties and heat transfer is limited and there is not ideal, causing much of the trapped heat to dissipate and not be exploited.
There are many severalcollectors; we can mention: solar collectors that are constructed with plastic, metal, vacuum and parabolic among others [1]. Each of these types of collectors has advantages and disadvantages that make it proper or improper for use. The plastic collectors, are very cheap and have high resistance to corrosion, they present a high thermal insulation but there are very fragile. Flat plate collectors,use metal sheets and tubes used to absorb solar radiation and there are a variety of proposed designs. Other collectors are those that use vacuum tubes. This, have the advantage of capturing more energy from the sun and convective losses are eliminated, but the cost is gets too high, compared to the previous two.
A traditional flat solar heater [2], basically consists in the following components:...