Atmospheric Steamer Pressure Control for Low Water Use
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Solution Overview
Problem
Conventional pressureless steam cookers face issues with excessive water consumption, low thermal efficiency, steam loss when the door is opened, and lime buildup, which affects energy efficiency and maintenance requirements.
Innovation Solution
A high-efficiency atmospheric steam cooker with two vertically stacked cooking compartments, each with a steam generator, a tempering tank, and a pressure-sensing device to control steam pressure, a gas burner for heating, and an integrated water filtration system to minimize lime formation, along with a design that reduces water usage and maintains optimal steam pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling water is sprayed into the exit steam to reduce temperature, then the steam temperature is reduced to comply with regulations, but water consumption increases significantly
Solution Approach 1:
The patent applies preliminary action by pre-cooling the steam in a heat exchanger before it reaches the drain line, using the temperature differential between hot exhaust steam and incoming cold water. This preliminary cooling action reduces the temperature of steam entering the cooking chamber, eliminating the need for excessive cooling water spray and reducing overall water consumption while still complying with temperature regulations.
2Productivity
If steam is supplied continuously to the cooking compartment, then the cooking process can be maintained, but thermal energy is lost when the door is opened
Solution Approach 1:
The patent implements feedback control by using a pressure sensor to monitor steam pressure in the cooking compartment and automatically adjusting the steam generation rate. When the door is closed and pressure builds up, the system reduces or stops steam generation. When the door is opened and pressure drops, the system automatically increases steam generation. This feedback mechanism maintains cooking productivity while minimizing thermal energy loss by matching steam supply to actual demand.
3Speed
If the steam flow rate is increased to accommodate frozen or room temperature food, then cooking can begin immediately, but excessive steam is consumed when less is needed later
Solution Approach 1:
The patent applies dynamics by making the steam flow rate variable rather than constant. The system dynamically adjusts the steam generation rate based on real-time conditions: high steam flow is provided initially for frozen or room temperature food to enable immediate cooking start, then the flow rate is automatically reduced as the food heats up and less steam is needed. This dynamic adjustment optimizes both cooking speed and energy efficiency throughout the cooking process.
4Ease of operation
If the door is opened frequently to inspect or work with food, then operational flexibility is improved, but steam pressure fluctuates and cold air enters the compartment
Solution Approach 1:
The patent uses feedback control to rapidly respond to door openings. When the door is opened, the pressure sensor detects the pressure drop and triggers an increased steam generation rate to compensate for the loss and maintain pressure stability. The system continues this elevated steam supply until the door is closed and pressure stabilizes again. This feedback mechanism allows operational flexibility for frequent door openings while automatically maintaining steam pressure stability within the cooking compartment.
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 steam cooker achieves a cooking energy efficiency of at least 38%, consumes less than 20 gallons of water per hour, and requires less maintenance, meeting Energy Star standards while being compact and user-friendly.
Implementation Method 1
a heat exchanger secured within the reservoir in a heat-transferring relationship at an exterior surface of the heat exchanger with the water held in the reservoir, and a heater that supplies heat to the interior of the heat exchanger
Implementation Method 2
a heat exchanger secured within the reservoir in a heat-transferring relationship
Implementation Method 3
a heat exchanger secured within the reservoir in a heat-transferring relationship
Implementation Method 4
A pressure-sensing device is disposed to measure the steam pressure in the at least one cooking compartment and to generate electrical output signals indicative of minimum and maximum pressure values
Data Source
AI summary
A pressureless or atmospheric steamer for cooking food with a high cooking efficiency has a cooking compartment with an outlet for steam and condensate that feeds to a tempering tank via an outlet conduit. The outlet conduit is spaced closely from the controlled water level in the tempering tank, and is in fluid communication with the atmospheric vent to create an open steam cooker. A steam generator is adjacent the cooking compartment and has a water reservoir, a heat exchanger secured within the reservoir in a heat-transferring relationship at an exterior surface of the heat exchanger with the water held in the reservoir, and a heater that supplies heat to the interior of the heat exchanger. The tempering tank has a drain and level controls for a water supply held in the tempering tank. A pressure-sensitive device is disposed to measure the steam pressure in the cooking compartment and to generate electrical output signals indicative of minimum and maximum pressure values to control the operation of the heater to maintain the steam pressure in the cooking compartment within that operating range. The steamer has an in-built water filtration system for water supplied to the water reservoir.