In air separation equipment, the cooling capacity resulting from the throttling effect is generated only by the gas (or liquid) passing through the throttle valve?

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In air separation equipment, is the cooling capacity resulting from the throttling effect generated only by the gas (or liquid) that passes through the throttle valve? In air separation units, the cooling capacity consists of two components: the cooling capacity provided by the expansion mechanism and the cooling capacity resulting from the throttling effect. After the expanded air from medium-pressure air separation units is liquefied in the lower column, it must pass through a liquid throttle to enter the upper column, whereas the expanded air from low-pressure air separation units does not go through a throttle valve. So, is it only the gas (or liquid) that passes through the throttle valve that generates the cooling effect through throttling? In fact, that’s not the case. The cooling capacity resulting from the throttling effect is due to the decrease in pressure, which leads to volume expansion; as a result, the potential energy of molecular interactions increases, thereby reducing the kinetic energy of molecular motion and causing the gas temperature to drop, which gives it the ability to absorb heat. For the entire air separation unit, the air pressure is high when it enters the unit and decreases as it exits; theoretically, the temperature can be reheated to the level it had when entering the unit. At this point, the enthalpy of the low-pressure gas is greater than that of the gas at the inlet; the difference in enthalpy between them represents the cooling capacity resulting from the throttling effect, regardless of whether this pressure drop occurs within the throttle valve. When gas expands in the expander, the cooling capacity of the expander is calculated by considering only the enthalpy drop resulting from the work done. In fact, as the pressure decreases, the molecular potential energy also increases; therefore, a certain amount of cooling capacity due to throttling effect should also be generated. This portion of the cooling capacity is not calculated separately; rather, it is represented by the total enthalpy difference between the low-pressure gas exiting the device and the high-pressure gas entering it, which reflects the overall throttling effect-based cooling capacity of the device. When adjusting the cooling capacity of the expander, it also does not affect the magnitude of the cooling capacity resulting from the throttling effect.