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Preparation method of lithium bromide absorption cycle working fluid

An absorption cycle, lithium bromide technology, applied in chemical instruments and methods, heat exchange materials, etc., can solve the problems of difficult product separation and purification, by-products, low cycle performance coefficient, etc., to achieve easy product separation and purification. , easy operation, high purity and high quality results

Inactive Publication Date: 2011-10-12
BEIJING UNIV OF CHEM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the cycle performance coefficients of the water-ionic liquid system proposed in this patent are all low
In addition, conventional ionic liquid synthesis methods generally use organic solvents, and there are by-products in the reaction process, which is not easy for product separation and purification.

Method used

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  • Preparation method of lithium bromide absorption cycle working fluid
  • Preparation method of lithium bromide absorption cycle working fluid
  • Preparation method of lithium bromide absorption cycle working fluid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Embodiment 1: the synthesis of ionic liquid [DMIm]Cl

[0026] This example is an example of self-synthesis of ionic liquid [DMIm]Cl. Measure 100 mL of N-methylimidazole with a concentration >99% after vacuum distillation and place it in a vacuumized 500 mL reaction kettle. While stirring with a stirrer, CH 3 Cl to 0.6MPa, react at a temperature of 50-70°C for 24 hours. The reaction equation is as follows:

[0027]

[0028] After the reaction was finished, nitrogen gas was introduced, and then the remaining methylene chloride and nitrogen gas in the still were drained, and a white solid product was obtained after cooling, with a yield of 98%.

[0029] The product obtained above was recrystallized three times in acetonitrile solvent, and then vacuum-dried at a temperature of 110° C. for 24 hours. The dried product appears as colorless or light yellow crystals at 25°C.

[0030] H NMR spectroscopy ( 1 HNMR) to characterize the structure of the product, the product ...

Embodiment 2

[0031] Embodiment 2: Add the thermophysical property change of ionic liquid [DMIm]Cl in lithium bromide aqueous solution

[0032] At room temperature, with the DMIm]Cl prepared in Example 1, according to the mass ratio of LiBr to [DMIm]Cl is 3:1, a saturated solution is prepared, the concentration mass fraction of solute (LiBr and [DMIm]Cl) is 69%, the boiling point It is 164.0°C. And at the same temperature, the boiling point of a saturated lithium bromide solution with a solute mass fraction of 60% is 155.5°C. Compared with the two, the boiling point of the new working fluid increases by 8.5°C, and the solubility increases by 15.0%. An increase in the boiling point of the system means a decrease in the vapor pressure of the system, and the solution at this time has relatively strong absorption characteristics for water vapor. The higher the concentration of the solution, the higher the boiling point rises, but the crystallization temperature limits the concentration of the...

Embodiment 3

[0033] At room temperature, according to LiBr vs. [DMIm]BF 4 The mass ratio is 4:1, and a saturated solution is prepared with a concentration mass fraction of 78% and a boiling point of 161.5°C. And at the same temperature, the boiling point of a lithium bromide saturated solution with a concentration mass fraction of 60% is 155.5°C. Compared with the two, the boiling point increased by 6.0°C and the solubility increased by 30.0%. Embodiment 4: Add the thermophysical property change of ionic liquid [EMIm]Br in lithium bromide aqueous solution

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Abstract

The invention relates to a preparation method of lithium bromide absorption cycle working fluid. A defined amount of imidazole type ionic liquid such as chlorinated 1,3-dimethylimidazole and 1,3-dimethylimidazolium tetrafluoroborate is added in lithium bromide aqueous solution working fluid, thus the refrigeration cycle performance coefficient can be increased and the problem that the lithium bromide aqueous solution working fluid is easy to crystallize and corrode can be relieved. The raw material cost and preparation cost of unit cycle working fluid can be reduced by 5-15%. In the method, the preferable ionic liquid [DMIm]Cl which is prepared by the gas / liquid phase synthesis method is added, organic solvent is not adopted, no byproduct is generated, the product is easy to separate and refine; and when the finished product is added in the lithium bromide aqueous solution working fluid, the lithium bromide absorption cycle performance can be obviously improved.

Description

technical field [0001] The present invention relates to the field of absorption cycle, in particular to an improved preparation method of lithium bromide absorption cycle working medium, the prepared lithium bromide absorption cycle working medium is suitable for various forms of lithium bromide absorption refrigeration / Heat pump unit. Background technique [0002] Under the great demand of energy saving and emission reduction, the lithium bromide absorption refrigeration / heat pump unit driven by low-grade heat has a wide application prospect, but the existing lithium bromide absorption cycle working fluid has the defects of easy crystallization and system corrosion in application , so improving the lithium bromide absorption cycle working fluid can improve the thermodynamic properties of the working fluid, alleviate its easy crystallization and corrosion to the system, and improve the heat conversion efficiency of the lithium bromide absorption refrigeration cycle. For ex...

Claims

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Application Information

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IPC IPC(8): C09K5/10
Inventor 郑丹星范丽华武向红董丽
Owner BEIJING UNIV OF CHEM TECH
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