Thermostat With Separate Heating And Cooling Elements
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Solution Overview
Problem
Existing thermostats for calorimeters face challenges in efficiently controlling temperature over a wide range for larger sample volumes while being compact, cost-effective, and maintaining the longevity of thermoelectric elements, particularly Peltier elements, which are prone to reduced service life when used for both heating and cooling.
Innovation Solution
A thermostat design featuring separate heating and cooling elements, with a constant coolant temperature, utilizing Peltier elements operated within their preferred direction, and a simple unipolar current source for efficient temperature control, allowing for a broader temperature range and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Peltier elements are used for both heating and cooling, then the thermostat can control temperature over a wide range, but the service life of the Peltier elements is reduced and maintenance costs increase
Solution Approach 1:
The thermostat is divided into separate heating and cooling systems. The cooling system uses Peltier elements to pump heat from the sample to a coolant, while the heating system uses a separate heating element. This segmentation allows each component to be optimized for its specific function, extending the service life of the Peltier elements while maintaining wide temperature control capability.
2Power
If Peltier elements are operated in overload mode to achieve higher heating capacity, then the heating performance is improved, but the service life is further reduced
Solution Approach 1:
By separating the heating function from the Peltier elements and assigning it to a dedicated heating element, the heating capacity can be increased without subjecting the Peltier elements to overload conditions. The Peltier elements operate within their rated capacity for cooling, while the heating element provides the additional heating power needed.
3Adaptability or versatility
If multi-stage Peltier elements are used to increase cooling capacity, then the temperature range is extended, but the device becomes more complex and expensive
Solution Approach 1:
A coolant is introduced as an intermediary substance to absorb heat from the Peltier elements. The coolant circulates through a heat exchanger, providing an efficient heat dissipation path that allows single-stage Peltier elements to achieve the same cooling capacity as multi-stage elements would provide, thereby simplifying the overall device structure.
4Adaptability or versatility
If the thermostat is designed for large sample volumes, then the applicability is improved, but the size and compactness of the thermostat are compromised
Solution Approach 1:
A coolant circulation system is implemented to efficiently remove heat from large sample volumes. The coolant flows through channels in thermal contact with the sample container, providing effective heat transfer without requiring the thermostat housing to be excessively large. This hydraulic heat removal system enables compact design while maintaining capacity for large samples.
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
Enables fast, precise, and efficient temperature control over a large range (up to -50°C to +200°C) with reduced power consumption and extended service life of thermoelectric elements, making it suitable for various sample volumes and applications.
Implementation Method 1
the amount of heat pumped due to the thermoelectric effect is proportional to the current flowing
Implementation Method 2
The heating element serves to supply heat to the sample directly or indirectly
Data Source
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AI summary
The thermostat has a sample (201), which is kept at a moderate temperature, and a heating element (202). The heating element supplies heat directly or indirectly to the sample. A thermoelectric cooling section (203) is thermally connected with a cooling agent (204). The cooling agent has a constant coolant temperature. An independent claim is included for a calorimeter.