Purging device, chiller equipped with same, and method for controlling purging device
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Solution Overview
Problem
The existing air bleeding devices in chillers require regular maintenance due to mechanical operation structures like float-type liquid level sensors, which are prone to abrasion and require complex maintenance procedures, involving contact with refrigerant liquids and system opening.
Innovation Solution
An air bleeding device that uses a pressure sensor and a cooler to detect the liquid level of refrigerant in the air bleeding tank by measuring pressure changes and condensation capacity, eliminating the need for float-type sensors and simplifying maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a float type liquid level sensor is used to detect the liquid level in the air bleeding tank, then the liquid level can be detected, but the mechanical operation structure causes abrasion in sliding portions requiring regular maintenance
Solution Approach 1:
The patent replaces the mechanical float-type liquid level sensor with a non-contact pressure sensor system. The pressure sensor detects pressure changes in the air bleeding tank, and the control unit calculates liquid level based on these pressure variations, eliminating mechanical moving parts and sliding portions that cause abrasion and require maintenance.
Solution Approach 2:
The patent introduces pressure as an intermediary parameter to indirectly measure liquid level. Instead of directly measuring liquid level with a mechanical float, the system measures pressure changes caused by liquid level variations and converts these pressure signals into liquid level information through control unit calculations.
2Measurement precision
If a float type liquid level sensor is used, then liquid level detection is achieved, but the float portion must contact refrigerant liquid surface requiring system opening for maintenance
Solution Approach 1:
The patent replaces the mechanical float-type liquid level sensor with a non-contact pressure sensor system. The pressure sensor detects pressure changes in the air bleeding tank, and the control unit calculates liquid level based on these pressure variations, eliminating mechanical moving parts and sliding portions that cause abrasion and require maintenance.
3Temperature
If the cooler cools the air bleeding tank to condense refrigerant, then refrigerant condensation occurs, but the cooling efficiency decreases when liquid refrigerant covers the cooling heat transfer surface
Solution Approach 1:
The patent implements a feedback control mechanism where the control unit continuously monitors pressure changes in the air bleeding tank and adjusts the cooler's operation accordingly. When pressure indicates sufficient condensation, the control unit modulates or stops cooling to prevent excessive liquid accumulation on the heat transfer surface, thereby maintaining optimal cooling efficiency while achieving the required condensation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables reliable detection of refrigerant liquid levels without float-type sensors, reducing maintenance complexity and improving maintainability by using pressure and condensation capacity measurements.
Implementation Method 1
a cooler (42) which cools an inside of the air bleeding tank (40) and condenses the refrigerant in the mixed gas
Implementation Method 2
an air bleeding tank pressure sensor (46) which measures a pressure in the air bleeding tank (40)
Data Source
AI summary
A purging device that includes a purging pipe for purging a gas mixture containing a coolant and a non-condensable gas from a chiller; a purging tank; a cooling device that has a cooling heat-transfer surface provided therein which condenses the coolant in the gas mixture and is oriented in the height direction inside the purging tank; a drainage pipe for discharging the liquid coolant inside the purging tank to the chiller; an exhaust; a purging tank pressure sensor for measuring the pressure inside the purging tank; and a control device which detects that an increase in the level of the liquid coolant inside the purging tank has occurred when the measured value from the purging tank pressure sensor decreases, and thereafter, increases to a prescribed value or higher, when condensing the coolant by cooling the interior of the purging tank using the cooling device.