The choice of fluid and thermal grid of the organic Rankine cycle in the conditions of its application at the oil refineries

The article discusses the problem of choosing the working fluid for the Rankine organic cycle. This is done by analyzing the parameters of the ORC unit on these Freon's. It is proposed to use low-grade heat of technological units for oil refining as a heat source for the organic Rankine cycle unit. Currently, a significant part of the available low-grade heat from oil refineries is lost into the atmosphere. The installation of the organic Rankine cycle allows the use of this heat to generate an expensive energy resource - electricity. This is the advantage of this installation over other methods of utilizing low-grade heat. At the moment, there is no clear methodology for choosing a working fluid for the organic Rankine cycle, that used at an oil refinery. For comparison, the following freons were selected: r245fa, r152a and r404a. To solve this problem, a model that calculates such indicators as thermal efficiency, coolant flow rate and electric power of the installation, for the simplest scheme of the organic Rankine cycle was built. The article also provides an analysis of the results obtained by modeling the comparison of the considered working bodies. To assess the feasibility of using the unit with selected coolant, the economic effect of its implementation was evaluated. One of the modern ways of recycling this low-grade heat is organic Rankine cycle (ORC). OCR works on the same principle as the classical Rankine cycle with water as a fluid. The main difference between organic fluid and water is a low boiling point, which allows steam to be generated at low temperatures of heat sources. In this regard, depending on the temperature conditions of the thermal scheme of the organic Rankine cycle, it is necessary to determine the compound that will be used as a working fluid. Based on this fact, the choice of the working fluid will be made according to the highest thermal efficiency of the cycle. The described method can also be used to select a working fluid for the ORC under other initial conditions. In the modern world, more and more attention is paid to the problem of improving energy efficiency.