Support Surface Air Conditioning for Evaporative Cooling Control
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Solution Overview
Problem
Existing microclimate management (MCM) capable support surfaces in hospital beds are limited by the properties of unconditioned ambient air, restricting their ability to achieve enhanced evaporative and heat withdrawal performance.
Innovation Solution
A method that involves chilling unconditioned ambient air to a temperature at least as low as required to achieve 100% relative humidity, demoisturizing it, and then optionally heating the chilled air before supplying it to the support surface to enhance evaporative and heat transfer performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If unconditioned ambient air is used for microclimate management, then the system is simple and energy-efficient, but the evaporative and heat withdrawal performance is limited
Solution Approach 1:
The patent changes the thermodynamic parameters of the air stream by chilling it to a temperature that achieves 100% relative humidity, then heating it to deliver a controlled temperature and humidity to the support surface. This parameter transformation enables enhanced evaporative and heat withdrawal performance while maintaining system controllability
Solution Approach 2:
The air is pre-conditioned (chilled and demoisturized) before being supplied to the support surface. This preliminary action of removing moisture through condensation during the chilling phase ensures that the air has optimal properties for enhancing evaporative performance without requiring complex real-time control during operation
2Reliability
If ambient air is chilled to achieve enhanced evaporative performance, then the evaporative capacity increases, but the energy consumption increases
Solution Approach 1:
The patent exploits the phase transition of water vapor to liquid during the chilling process. When ambient air is chilled to 100% relative humidity, water vapor condenses into liquid, automatically removing excess moisture from the air. This phase change mechanism provides natural demoisturizing without requiring additional energy-intensive dehumidification equipment
Solution Approach 2:
The system operates in cycles, chilling air to condense moisture, then heating and delivering it to the support surface. This periodic operation allows the system to accumulate cooling capacity during off-peak times and deliver it when needed, optimizing energy usage while maintaining enhanced evaporative performance
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 method significantly increases the evaporative and heat withdrawal capacity of the support surface, providing improved cooling and moisture management for bed occupants, potentially reducing the risk of pressure ulcers and skin tissue breakdown.
Implementation Method 1
chilling the unconditioned ambient air to a temperature at least as low as that required to achieve 100% relative humidity, thereby demoisturizing the air
Implementation Method 2
heat transfer from the occupant's skin can cause molecules of perspiration present at the interface between the support surface and the occupant's skin to acquire enough energy to break free, i.e. evaporate
Implementation Method 3
a stream of air flows through the interior of the support surface. Provided the air is cooler than the occupant's skin, the internal airstream acts as a heat sink
Data Source
AI summary
A method for controlling performance of an MCM capable support surface having a flowpath for guiding a stream of air along at least a portion of the surface, comprises specifying a desired evaporative rate greater than an evaporative rate achievable with unconditioned ambient air, chilling the unconditioned ambient air to a temperature at least as low as that required to achieve 100% relative humidity, thereby demoisturizing the air, and supplying the chilled, demoisturized air to the flowpath. The method may also include the step of heating the chilled, demoisturized air prior to step of supplying it to the flowpath. A system for carrying out the method includes a microclimate management (MCM) capable support surface 22, a chiller 60 for cooling air to be delivered to the MCM capable surface, a user interface 42 for receiving instructions concerning desired microclimate management performance, and a controller 50, responsive to the instructions, for operating the chiller.