Dual-Loop Vapor Pressure Control for Drying and Curing Rooms
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Solution Overview
Problem
Conventional methods for controlling temperature and humidity in drying and aging processes, such as those for cannabis, cheeses, and meats, are inefficient and unstable, leading to inconsistent product quality due to fluctuations in vapor pressure and moisture loss rates.
Innovation Solution
A dual-control loop system that independently regulates dry bulb temperature and vapor pressure (or dew point) using PID control loops and a cooling coil with adjustable temperature and air flow, allowing precise control of moisture loss and environmental conditions during the drying and curing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single-point humidity control systems are used to control % RH in a room, then the system is simple to operate, but the control is unstable and inconsistent when temperature fluctuates
Solution Approach 1:
The control system is segmented into two independent control loops: a first control loop that controls dry bulb temperature, and a second control loop that controls vapor pressure (dew point). This segmentation allows each loop to independently manage its specific parameter without interference, resolving the instability caused by temperature fluctuations affecting humidity control.
Solution Approach 2:
The system implements feedback control in both loops, where the first control loop receives feedback from temperature sensors and the second control loop receives feedback from dew point sensors. This feedback mechanism ensures that each parameter is continuously monitored and adjusted to maintain stable control, preventing the oscillations that occur in conventional single-loop systems.
2Manufacturing precision
If conventional temperature and humidity control facilities are used to control drying and curing processes, then the system can maintain basic environmental conditions, but the vapor pressure control is insufficient leading to inconsistent moisture loss rates
Solution Approach 1:
The control system is segmented into two independent control loops: a first control loop that controls dry bulb temperature, and a second control loop that controls vapor pressure (dew point). This segmentation allows each loop to independently manage its specific parameter without interference, resolving the instability caused by temperature fluctuations affecting humidity control.
Solution Approach 2:
The system changes the control parameter from relative humidity to vapor pressure (dew point) in the second control loop. This parameter change enables direct control of the moisture loss rate, as vapor pressure is the fundamental driver of moisture transfer from the product to the environment, providing more precise manufacturing control.
3Loss of energy
If cooling coils are used to control vapor pressure by condensing moisture, then the vapor pressure can be reduced, but energy is wasted when the coil temperature is not optimally controlled
Solution Approach 1:
The second control loop uses feedback from dew point sensors to continuously monitor vapor pressure and adjust the cooling coil operation accordingly. This feedback control ensures the cooling coil operates only when and to the extent needed to achieve the target dew point, preventing energy waste from over-cooling while maintaining precise vapor pressure control.
Solution Approach 2:
The system dynamically adjusts the cooling coil temperature and operation based on real-time dew point measurements and control algorithm calculations. This dynamic control allows the system to optimize energy usage by adjusting the cooling intensity to match the actual vapor pressure conditions, rather than operating at fixed settings.
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
This system ensures consistent vapor pressure and controlled moisture loss, resulting in higher-quality products by maintaining optimal drying and curing conditions, independent of ambient climate, and reducing energy waste and product variability.
Implementation Method 1
The vapor pressure in the room is typically reduced with the use of a coil that has a surface temperature that is below the dew point of the air in the room. Since this surface is below the dew point, condensation forms removing water vapor from the air in the room
Implementation Method 2
In the aging/drying process of food products, water is released from the product in the form of water vapor
Data Source
AI summary
A system to control the conditions of an aging room, also known as a conditioned space, for products in which independent feedback loops control the dry bulb temperature and the dew point while controlling the difference between the vapor pressure in the room and the vapor pressure of the products being dried, thereby controlling the amount of and rate of water or water vapor loss of the products and, therefore controlling its quality, the system also including target controls, a thermoelectric cooler and lighting controls.