Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
MODELING AND ANALYSIS OF BUBBLE PUMP PARAMETERS FOR A SOLAR-POWERED REFRIGERATOR BY DIFFUSION AND ABSORPTION FOR VACCINE STORAGE IN REGIONS WITHOUT ELECTRIFICATION
Submission Author:
Rafael Teixeira Mendes , MG , Brazil
Co-Authors:
Rafael Teixeira Mendes, Luiz Machado, Márcio Cortez, Pedro Antonio Diniz Chaves, Kássio Nogueira Cançado, Fabiano Drumond Chaves
Presenter: Rafael Teixeira Mendes
doi://10.26678/ABCM.COBEM2021.COB2021-0397
Abstract
A small diffusion absorption refrigerator commonly used in hotel’s rooms favors the conversion of its heat source to solar energy because the original heat source of the bubble pump is a 80 W electric resistor. The conversion of this power to the solar type can be done by replacing the electric resistor by a heat exchanger involving the bubble pump, inside which flows thermal oil heated in a concentrating solar collector. The two main objectives of the current work are the design of this heat exchanger and the analysis of thermohydraulic parameters of the system. This analysis was performed using a steady state model based on the application of energy and mass balance equations for thermal oil circulating into the heat exchanger of the bubble pump of a Dometic mini fridge loaded with ammonia, water and hydrogen. Equations were also applied to estimate the loss pressure along the oil circuit. The model, written in software EES (Engineering Equation Solver), was fed with the correlation of Churchil and Chu to evaluate the heat transfer between the oil and the external tube of the bubble pump, as well as with a temperature of 165ºC on the external wall of the bubble pump, whose value was obtained from experimental tests carried out in the refrigerator. The coaxial type heat exchanger has been designed with a length of 10 cm equal to that of the electric resistor of the refrigerator, and a diameter of 20 mm, which is 4 mm larger than the diameter of the outer tube of the bubble pump. Several thermal oils from the EES database were tested, of which the Therminol-VP1 was chosen as the most suitable for the heat exchanger operation. Therminol-VP1 allowed heat to be transferred at the rate of 80 W to the poor ammonia/water solution in the bubble pump with a mass flow rate of only 7,8 g.s-1, resulting in a small pressure loss and an average temperature around 207°C in the oil circuit, a relatively low value that can be obtained in the concentrating solar collector.
Keywords
Diffusion absorption refrigerator, Bubble Pump, Solar Energy, Vaccine storage, Model, Heat transfer
