Papers by Keyword: Bubble Pump

Abstract: Increase in the consumption of electrical energy worldwide has laid the emphasis on replacing electrical energy with thermal energy wherever possible. In this paper, the bubble pump, which is ‘heart’ of diffusion- absorption refrigeration system, has been investigated numerically. A thermally driven bubble pump, which can be powered by waste heat or solar thermal energy, is used to lift the liquid. As a result of the absence of any mechanical moving part, the refrigerator is silent and very reliable in addition to an economical and environmental friendly device. The concept of such a pump is already in existence but optimization studies are yet to be extensively investigated. This paper deals with the optimization of various parameters of the bubble pump using water as the working fluid. Parametric studies are carried out and a design optimization for maximum efficiency is performed for various operating conditions. Numerical simulation of the bubble pump is carried out using simple numerical equations which assume slug flow in the bubble pump. The diameter of the pipe and the position of the heating element are varied and the effect it has on time taken, pumping ratio and pumping ratio for one pumping cycle is studied.

Abstract: Compared with the gas-compressed refrigeration system, the diffusion absorption refrigeration cycle has no moving part and the associated noise and vibration. It can be operated without any electric input and driven by various energy sources, has no the problem of the substitute of CFC, furthermore it has positive significance in energy conservation, off peak, environmental protection, and promoting the use of gas. So it has broad application prospects as a kind of absorption refrigeration mode. In the development of diffusion absorption refrigeration technology, the performance of diffusion absorption refrigeration system has been improved and enhanced continuously. The paper presents and discusses the recent research progress of diffusion absorption refrigeration which contains design of bubble pump, adjustment and optimization of operation parameters, utilization of low-grade thermal energy and selection of working medium. The research direction of diffusion absorption refrigeration in the future is suggested.

Abstract: In this paper, a novel MEMS-fabricated thermal bubble pump is proposed. By using thermocapillary effect in a microchannel loop, bubbles are designed to move only in one direction of the loop. Driving heater with a square-wave signal, bubble nucleates and grows asymmetrically above the heater. As soon as the heating pulse is turned off, an interesting phenomenon is found. Instead of bubble collapse, bubble moves toward growing direction. Continuous bubbles grow and move periodically when square-wave pulsing signals are applied. Thermocapillary pumping phenomena are achieved successfully in the experiments. By adjusting background temperature field, thermocapillary pumping phenomena can be sustained. Detailed mechanism for pumping force will be discussed in this paper.