A screw expansion (compression) machine with variable volume ratio

Abstract

The invention discloses a screw expansion (compression) machine with variable volume ratio. The screw expansion (compression) machine comprises a box body (300), an upper supporting end cover (400), an air inlet end cover (500) and a valve core cover plate (600). The upper supporting end cover (400) is fixedly connected with the box body (300) to form a closed cavity (408), the air inlet end cover(500) and the valve core cover plate (600) are arranged in the cavity (408), and the valve core cover plate (600) is arranged below the air inlet end cover (500). A screw expansion machine further includes a main drive shaft (401), an adjusting operating rod (402) and a driven shaft (403), wherein the main drive shaft (401), the adjusting operating rod (402) and the driven shaft (403) are arranged in parallel to each another. The screw expansion machine further includes an air inlet adjusting mechanism arranged in the cavity (408), and the air inlet adjusting mechanism comprises a half-gear cam (700), an adjusting gear (800), a valve core pushing rod (900), a radial sliding spool (603) and a circumferential sliding valve core (604). The screw expansion (compression) machine has an adjustable built-in volume ratio, the optimal matching between the built-in volume ratio and the actual operating pressure ratio of a system can be kept to the greatest extent, and the overall operating efficiency of the screw expansion machine under variable operating conditions is improved.

Description

Technical field [0001] The invention belongs to the technical field of energy utilization and conversion, and in particular relates to a screw expansion (compression) machine with a variable volume ratio. Background technique [0002] With the increasing awareness of human beings on energy saving, emission reduction, and low-grade energy utilization, the development of geothermal resources, industrial waste heat utilization, biomass energy conversion, and the development and conversion of solar and wind energy storage technologies have made it based on Rankine The demand for circulating small and medium thermal power machinery is also increasing. [0003] Small and medium-sized thermal power machines are mostly volumetric expanders, including twin-screw expanders, single-screw expanders, scroll expanders, sliding vane expanders, rotary piston expanders, and so on. Among them, in the use of thermal energy on a scale of 100kW or more, twin screw expanders are mostly used. However, ...

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Problems solved by technology

The price for this is that there is always an additional heat loss during the expansion process as the expander deviates from the best fit

[0004] In addition, since the built-in volume expansion ratio of the volumetric expander is mostly determined by the geometry of the rotating parts, the volumetric expander with a specific built-in volume expansion ratio usually also has its rotating parts specially designed, and the corresponding parts are customized and processed, resulting in Expansion machine manufacturing cost is high

Especially when a high built-in volume expansion ratio is required, because it is more difficult to manufacture an expander with a high built-in volume expansion ratio, some heat recovery systems have to choose expanders with a low built-in volume expansion ratio in series to achieve multi-stage expansion, resulting in heat Recovery and development system equipment cost is too high

In addition, due to the limitation of low built-in volume expansion ratio, many low-grade thermal energy conversion development systems can only use organic working fluid as the thermal energy conversion medium, which is not only expensive, but also often flammable, explosive, or toxic, or harmful to the atmospheric greenhouse effect. Potential threats, also because organic working fluids usually have low specific heat capacity, a larger fluid mass flow rate is required in the thermal system, and more pump power consumption is consumed, resulting in a reduction in the net power of the thermal cycle system and lower system efficiency

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