Thermodynamic analysis of lithium bromide absorption chiller driven by geothermal energy
The use of geothermal energy as a heat source to drive vapor absorption chillers has been receiving more interest. Geothermal energy is sustainable, economically viable and environmentally friendly. Absorption chillers powered by geothermal energy are still in their development phase. In this work, a lithium bromide absorption chiller operated with a geothermal heat source will be thermodynamically analyzed. The focus will be on the solution heat exchanger performance, in particular, the effect of geothermal heat source fluid temperature as well as mass flow rate on the absorption chiller coefficient of performance (COP). The effectiveness of the solution heat exchanger will be also studied and evaluated. Preliminary results showed that as the pressure in geothermal water vapor separator increased from 0.23 to 0.45 MPa, the absorption chiller cooling load increased by 28% while the COP decreased by only less than 1.4% at the same condenser pressure.
Parametric Study of a Single Effect Lithium Bromide-Water Absorption Chiller Powered by a Renewable Heat Source
This work investigates the performance of a single-effect absorption chiller utilizing an aqueous lithium bromide solution as the working fluid and driven by hot fluid rejected from either a geothermal power plant or the outlet of a thermal solar collector. This relatively low enthalpy return fluid, which will otherwise be reinjected back into the earth, will be utilized as the thermal energy source of the chiller. Although such chillers are considered low-grade energy refrigeration cycles, the one proposed here has an advantage in terms of economy and efficiency. A parametric analysis is performed using Engineering Equation Solver software and is used to highlight the effect of the heat exchanger size on the coefficient of performance of the chiller. The analysis proved that the proposed device can operate with excellent cooling capacity, reaching 16 kW, and a relatively high coefficient of performance (~ 0.7) while being driven by the low-grade energy. The heat source temperature, solution heat exchanger effectiveness and the size of the absorber were shown to be key parameters for the design and operation of absorption chillers. Moreover, increasing the heat source mass flow rate has a significant impact on both cooling capacity and coefficient of performance at low values (< 10 kg/s) and unnoticeable impact at higher values (> 10 kg/s). * Corresponding author Tawalbeh, M., et al. Parametric Study of a Single Effect Lithium ... Year 2020 Volume 8, Issue 3, pp 464-475 465 Journal of Sustainable Development of Energy, Water and Environment Systems
The measuriment of ferromagnets magnetic characteristics using Labview software
The digital method of measurement and registration of dynamic loops hysteresis family of magneto-soft materials where, along with known analogues from electro-technical steel, magnetic materials with considerably smaller specific magnetic losses such as amorphous alloys on the basis of iron, is offered. Tests of magnetic properties of materials are carried out on the base of the hardware-software measuring complex in which along with the standard established electric equipment and USB oscillograph for realization of a digital method, the software for the personal computer developed in the environment of visual programming of Borland Delphi 7.0, connected through the ActieveX technology with the Labview 7.0 environment, is applied. The software allows carrying out input of basic data concerning geometry of prototypes of cores from magnetic materials and numbers of rounds of the magnetizing and measuring windings located on their surface. Experimental data on voltage at measuring winding terminals are processed by means of the virtual integrator in a Labview package. The developed software provides the possibility of saving the obtained hysteresis loop in the form of a text file, and creation of the hysteresis loops family on the virtual oscillograph screen.