Cold Storage Air Curtain Control for Ice and Fog Prevention

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Solution Overview

Problem

Conventional air curtain systems for cold storage doorways are inefficient and prone to forming ice, water, and fog due to inadequate temperature control, especially in dynamic environments and multiple air curtain arrangements, where they struggle to respond quickly to changing conditions and accurately monitor humidity and temperature.

Innovation Solution

An air curtain arrangement with a control system that continuously monitors air stream temperature and humidity ratios across a doorway, using sensors to adjust the heater operation to maintain the air stream temperature in a non-saturated state, preventing ice and fog formation by keeping the air stream temperature above the psychrometric saturation curve.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the air stream temperature is increased to prevent ice and fog formation, then the reliability of preventing condensation is improved, but the energy consumption increases

Engineering Contradiction:

Improveprevention of ice and fog formationVSAvoidheater energy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The control system continuously monitors air stream temperature and humidity ratio, and dynamically adjusts the heater operation to maintain the air stream in a non-saturated state. This feedback mechanism ensures ice and fog prevention while minimizing energy consumption by heating only when and to the extent necessary.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically conditions the air stream by continuously adjusting the heating based on real-time temperature and humidity measurements. This dynamic control allows the system to adapt to changing environmental conditions, maintaining reliability while optimizing energy usage rather than using fixed high-temperature settings.

Inventive Principle:

Principle #15Dynamics

2Use of energy by moving object

If conventional control systems operate the air curtain at points directly on the saturation curve, then the energy consumption is reduced, but the reliability of preventing ice and water formation deteriorates

Engineering Contradiction:

Improveheater energy consumptionVSAvoidprevention of ice and water formation

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The control system uses continuous monitoring of temperature and humidity ratio with feedback control to maintain the air stream in a non-saturated state. This prevents the system from operating at or near the saturation curve where ice and water formation occurs, while still minimizing energy consumption through precise control.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system takes preliminary action by maintaining the air stream temperature above the saturation curve before ice or water can form. This proactive approach prevents condensation and freezing by keeping the air in a safe non-saturated state, rather than reacting after problems occur.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If mathematical approximations of the psychrometric saturation curve are used, then the device complexity is reduced, but the measurement precision deteriorates

Engineering Contradiction:

Improvecontrol system complexityVSAvoidsaturation curve accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The control system uses feedback from precise temperature and humidity ratio measurements to determine the actual saturation curve position and adjust the air stream accordingly. This feedback approach maintains accuracy without requiring complex pre-calculated mathematical approximations, as the system adapts to actual conditions in real-time.

Inventive Principle:

Principle #23Feedback

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 system effectively prevents condensation and formation of ice, water, and fog by dynamically adjusting the air stream temperature based on real-time humidity and temperature readings, ensuring efficient operation even in complex multiple air curtain setups.

Implementation Method 1

A heater warms the air stream

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

Air curtains generally direct air across the doorway to counter infiltration of warm to the cold room and exfiltration of cold air from the cold room

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS8287337B2Cold storage doorway with airflow control system and method

Publication Date: 2012.10.16 HCR INC

AI summary

A conditioned vestibule, control system, and method are disclosed for use with a cold storage doorway that separates warm and cold sides. A heater warms an air stream discharged across the doorway by the vestibule. A control unit operates the heater to maintain an air stream temperature. The control unit continuously monitors the air stream temperature and operates the heater to maintain the air stream temperature in a non-saturated state based on a humidity ratio. One embodiment calculates first and second temperatures based, respectively, warm and cold side tangent lines to a psychrometric saturation curve and based on the humidity ratio. The tangent lines are based on humidity and temperature sensed on the warm and cold sides. The air stream is warmed to at least the greater of the first and second temperatures. One embodiment controls air flow to adjust the humidity ratio to more efficiently operate the vestibule.