Probe apparatus and method for measuring cryogenic exhaust flow
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Solution Overview
Problem
Existing industrial freezer systems face challenges in accurately measuring cryogen exhaust flow due to ice accumulation and low temperatures, leading to inefficiencies, increased maintenance, and safety risks.
Innovation Solution
A flow probe apparatus with a resistive heater and control circuit that operates at varying temperatures to determine a heat transfer coefficient, allowing for accurate measurement of cryogen exhaust gas velocity without ice buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing measurement devices are used in cryogenic environments, then measurement function is provided, but ice accumulation occurs on the devices leading to inaccurate readings and operational failure
Solution Approach 1:
The flow probe is operated in oscillating temperature modes (elevated temperature mode and ambient temperature mode) rather than continuously at ambient temperature. This parameter change prevents ice accumulation by periodically heating the probe above freezing point, thereby maintaining measurement reliability in cryogenic exhaust environments
Solution Approach 2:
The control unit alternates the flow probe between elevated temperature mode and ambient temperature mode in periodic cycles. During elevated temperature mode, the heater operates to prevent ice formation; during ambient temperature mode, accurate flow measurements are taken. This periodic action resolves the contradiction between maintaining measurement accuracy and preventing ice accumulation
2Measurement precision
If the flow probe is kept at ambient temperature for accurate measurement, then measurement accuracy is maintained, but ice accumulation occurs causing device failure
Solution Approach 1:
Before ice accumulation can occur during ambient temperature measurement mode, the control unit periodically switches the probe to elevated temperature mode where the heater prevents ice formation. This preliminary anti-action (preventive heating) counteracts the harmful effect of ice accumulation before it can compromise the measurement device
Solution Approach 2:
The control unit proactively alternates the probe to elevated temperature mode before ice accumulation becomes problematic. By periodically pre-heating the probe, the system prevents ice formation that would otherwise occur during extended ambient temperature measurement periods
3Productivity
If exhaust system components operate continuously in cryogenic conditions, then freezing process continues, but components become fouled and inoperable requiring shutdown for maintenance
Solution Approach 1:
The oscillating temperature operation mode enables the flow probe to continuously perform its measurement function without interruption for maintenance. By periodically switching to elevated temperature mode to prevent ice accumulation, the probe maintains continuous operational capability, eliminating downtime associated with ice-related failures and ensuring continuous monitoring of the freezing process
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
The solution provides continuous, reliable, and efficient measurement of cryogen exhaust flow, reducing downtime, maintenance, and improving safety in industrial freezing processes.
Implementation Method 1
The flow probe may include a heater, such as a resistive heater
Data Source
AI summary
An apparatus for measuring flow of cryogen exhaust gas from a freezer includes a flow probe with a resistive heater and a flow probe control. The flow probe control is coupled to the flow probe and the flow probe control includes a control circuit configured to operate the resistive heater at a first temperature for a first period of time, operate the resistive heater at a second temperature for a second period of time, and determine a heat transfer coefficient at the flow probe. The first temperature and the second temperature are different and at least one of the first and second temperatures is greater than a predetermined threshold temperature. A related method is also provided.