Internal energy and exergy recovery in high temperature application absorption heat transformers
Abstract In this paper, the design of a triple absorption heat transformer (TAHT) using the working fluids water and lithium bromide is dissected and reassembled using heat exchange network modelling in order to determine the optimum number and locations of internal heat exchange units within the system. It is found that the conventional design of the TAHT does not employ heat exchangers effectively, and that thus by rearranging these units system COP may be increased by 11.7% while exergy destruction within the system (its irreversibility) can be reduced by 21%. Strategically adding an extra one or two heat exchangers increases the COP by 16.4% and 18.8% while decreasing exergy destruction by 28% and 31.5% respectively compared to a conventional TAHT design.
Experimental analysis of the rate of absorption of steam bubbles in lithium bromide solution for use in an absorption heat transformer
An experimental investigation is conducted into the absorption of steam bubbles in a concentrated lithium bromide solution. The aim of the work is to determine whether such bubble absorption may be advantageously utilised within the absorber column section of an absorption heat transformer system. A glass bubble column is constructed and a high speed camera is used to track the collapse of steam bubbles at different temperatures and solution concentrations. A simple ordinary differential equation model is developed which is capable of explaining 96% of the observed experimental variance. Very high mass transfer coefficients of ~0.012m/s are observed which indicates that this method of absorption may have significant advantages over alternative methods previously examined.
Simulating the Illuminance and Efficiency of the LEDs Used in General Household Lighting
Abstract The advantage of the LEDs illumination in general household lighting was proposed. High efficiency white LED as the light source was provided the energy saving illumination of the general household lightings. Different spaces in general household with different standards of average illuminance were designed and simulated by LightTools and DIALux software. The power consumptions and efficiency of traditional illuminated light sources and LED light source in lighting the household environment were analyzed and compared with each other at the same standard of average illuminance. Finally, it provided the advantage of using white LEDs in different spaces of the general household lighting.