CO2 Rankine cycle system for heavy-duty diesel engine waste heat gradient utilization

Abstract

The invention discloses a CO2 Rankine cycle system for heavy-duty diesel engine waste heat gradient utilization. The CO2 Rankine cycle system is a special CO2 Rankine cycle system with CO2 serving as a working medium, waste heat of diesel engine high-temperature flue gas serving as a heat source, and a waste heat driving absorption refrigeration product of diesel engine cooling system hot water serving as a cold source. The CO2 Rankine cycle system is mainly composed of a flue gas waste heat exchanger, CO2 turbines, power equipment, a regenerator, a condenser, a high-pressure pump, a flue gas water heater and an absorption refrigerator. The characteristic that the condensation enthalpy of the CO2 working medium near the critical point is reduced is skillfully utilized; and the efficiency of conversion of heat into power is higher than that of an ORC cycle or other cycles and is obtained through a special cascade stage combined cycle formed by high and low grade waste heat, so that the fuel oil use ratio of a diesel engine is increased by 18%-25% or above. The CO2 Rankine cycle system for heavy-duty diesel engine waste heat gradient utilization is capable of achieving waste heat power generation / driving, heat supply and refrigeration poly-generation and has remarkable economic benefits, social benefits and application prospects.

Description

technical field [0001] The invention belongs to the field of mechanical engineering and energy saving, and in particular relates to a CO 2 Rankine cycle system. Background technique [0002] Heavy-duty diesel engines are the main power equipment for ships, ships, oil exploration and distributed power generation, and consume a large amount of oil resources every year. However, affected by various factors, the power output work of heavy-duty diesel engines in actual operation only accounts for 40-50% of the total heat of fuel combustion, and the rest of the fuel energy is dissipated into the atmosphere through exhaust gas, cooling system and lubricating oil system. . Among them, the heat energy contained in the tail gas accounts for about half of the total waste heat energy, and the temperature can reach 250-500 °C. The power efficiency of the gas turbine is lower, usually within 40%, and its exhaust energy is higher and the temperature is higher. Efficient use of these wa...

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Problems solved by technology

[0007] However, as summer ambient temperatures in most parts of the world approach or exceed CO 2 critical temperature, it is impossible to use natural cold sources to convert CO 2 Condensed into liquid, Brayton cycle has to be used in engineering applications, or Brayton cycle and Rankine cycle dual mode operation, but the system is too complicated

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