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| Completed Projects and Presentations on ITE: | ||||||||||||
| A numerical study of roof-spray evaporation for cooling load reduction, (Engr. Samuel Sanchez; completed MEP thesis Sept. 2003).� Evaporative cooling of roof has been used in some hot climate countries.� Heat from outside that arrives on the roof is cooled down prior to its entry into the room.� This can be achieved by spraying it with water and allowing the water to evaporate to the ambient.� | ||||||||||||
| ����������� The study determines the applicability of this cooling method to built indoor environments in Cebu area.� A computer simulation model that predicts the roof temperature and heat flux of a water-sprayed roof is developed using the principles of transient heat transfer through a composite roof material and using a finite-difference solution to the governing equation.� The simulation is based on a roof construction commonly found in this region and uses the climatic data of Cebu.� Two cases are tested:� the sprayed and the unsprayed roof system.� The effect of the spraying of the roof is determined by comparing the result of these cases.� Results for ceiling temperature and heat flux values are reported for the months of April, August, and December.� The effects of the roofing materials on the temperature and heat flux are also reported.� Results show that spraying of the roof reduces heat flux by 55 percent while it reduces the ceiling temperature by 25 percent. | ||||||||||||
| Analysis of earth-tube heat exchanger using finite difference method, (Engr Paul Sanut; completed MEP thesis March 2002). High energy cost has motivated the development of alternative ways of cooling the indoors.� A very promising alternative is the use of� Earth-Tube Heat Exchanger, which is simply� a galvanized iron pipe, single or multiple pipes, ��horizontally �buried in the ground at depths of around 2 meters, where temperature of the soil is fairly constant and significantly lower that the outside air.� One end of the pipe is open to the outdoor while the other end is connected to the indoor.� Outdoor air is conveyed through this pipe either by small mechanical blowers or by natural convection driven �by buoyancy forces.�� As air flows through the pipe, it rejects heat to the ground causing air temperature to drop; and the cooled air leaving the pipe is now capable of cooling the indoors.� The study aims to developed a simulation model that can predict the air temperature leaving the pipe.� The model is based on the governing equations for two dimensional transient heat conduction in the ground soil and �forced convection of air in the pipe.� These equations were solved by finite difference approach.�� The �data input needed ��are values of soil properties, inlet air temperature, and pipe dimensions. ��The effects of the cyclic variation of inlet temperature and the saturation of soil temperate were carefully analyzed.� The model can serve as effective analytical tool for engineers designing earth-cooled tubes. � | ||||||||||||
| Flow rate characteristics of buoyancy-induced airflow in open-ended vertical structures, (Oral presentation, 2nd International Engg. Research Conference,IERC2006, Cebu. N.Buenconsejo Jr.)� Buoyancy-induced airflow in two types of open-ended vertical structures: a partly-heated and partly cooled vertical duct, and a combination of� a side-heated box and vertical duct are experimentally studied.� A flow rate prediction method based on buoyancy and flow resistance balance is proposed and experimentally validated for flow rates G <0.15 kg/m2s� in the case of� the partly heated partly cooled duct and� Reid < 700 in the case of box and duct combination�� In both cases predicted values agree well with� measured values, -with deviations within 10 percent, provided that in� the computations� buoyancy is based on average air temperature.� For the box and duct combination, buoyancy and pressure defect vertical distributions predicted by the proposed model agree well with measured values.� | ||||||||||||
| Estimation of gas flows under natural convection in vertical channels using the equation for an equivalent� situation with forced convection.� (Proc. of the 1st International Engineering Research Conference,IERC2005, 47-56. N. Buenconsejo Jr., M. Loretero, and J. Pastoril).��A simple method for predicting the natural convection mass flow rate inside a uniformly heated vertical circular channel is presented.� An equation for the average mass velocity inside the channel is derived from momentum equation that is made one-dimensional by using cross-sectional average values and by introducing the assumption that the flow is hydrodynamically developed from the channel inlet up to its exit.� The buoyancy and friction terms in this equation as well as the pressure losses at the entrance and exit of the channel are evaluated using equations for an equivalent situation with forced convection.� The validity and the accuracy of this method was confirmed by comparing it with the currently accepted 2-D analysis in terms of dimensionless flow rate, dimensionless heat transfer coefficient, and dimensionless pressure defect in the range of dimensionless channel length from 0.01 to 1.0.� The simple model can accurately predict the� flow rate provided that the head loss due to entrance flow development is considered.� The simple model shows similar flow rate characteristics as the 2-D analysis and it approaches the same limiting value for flow rate.� The dimensionless heat transfer coefficient of the simple model agrees well with that of 2-D analysis, which means that the thermal characteristics of natural convection inside a vertical channel is similar to that of an equivalent forced convection. | ||||||||||||