Abstract

The purpose of the article is to analyze the energy efficiency of resorption refrigeration cycles, which can contribute to energy conservation during cooling of liquid and gaseous products in agriculture and other industries. It is known that the Lorentz cycle is exemplary for cooling processes and, unlike the Carnot cycle, is thermodynamically more efficient due to the change in the temperature of the cooling fluid. Cycles with stepped resorption operate on the Lorentz principle, but further scientific studies are needed to introduce them into the industry. In the absorption cycles, the product is cooled in the degasser when the solution is boiled in a predetermined temperature range. The solution is taken from the last resorption step and throttled into the cold end of the degasser. In the degasser, the solution boils at constant low pressure and temperature rise in accordance with the interval of change of temperature of the cooled product. The steam formed is compressed by the compressor and fed from the degasser to the resorber. A low concentration solution from the warm end of the degasser is also pumped there. In the resorber steam is partially absorbed by the solution when the heat is discharged into the environment. Next, the steam continues to be absorbed in the resorbers, which are cooled by the boiling solution. Part of this solution is taken from the entrance to each resorber and throttled into the degassing cavity that cools the resorber. Increasing the number of resorption steps makes it possible to increase the concentration of the solution and lower its temperature after throttling into the degasser, or to reduce the ratio of the resorption pressure to the degassing pressure. It should be noted that in cycles on solutions, in contrast to cycles on pure agents, there are two degrees of freedom that are chosen to obtain a given cooling temperature - it is not only the pressure but also the concentration of the solution that complicates the calculations. Therefore, a generalized technique for the thermal calculation of cycles with different number of absorption steps is developed to cool the flow of substances from ambient temperature to a given low temperature. According to the developed methods of construction and calculation of cycles on ammonia solution in water, the specific energy efficiency of cycles and the degree of compression of steam in the compressor are analyzed, depending on the cooling temperature and the number of resorption stages. Comparison of indicators with two-stage ammonia cycle is given. The analysis shows the higher energy efficiency of the resorption cycles, and that with the increase in the number of resorption rates in the cycles, the ratio of the resorption pressures and degassing decreases. This allows the steam to be compressed in efficient turbochargers or in thermal compressors when using heat of low temperature potential, which will also contribute to energy conservation during cooling of liquid and gaseous products in various industries, including in agriculture.

resorber, rezorber, step, cycle, coolings, cold