Reciprocating Compressor Recesses for Reduced Heat Transfer
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Solution Overview
Problem
Reciprocating compressors, particularly those using carbon dioxide as refrigerant, suffer from significant heat transfer from the delivery chamber to the crankcase, leading to increased compressor temperature and reduced efficiency, while existing solutions either increase manufacturing costs or dimensions.
Innovation Solution
A crankcase made from spheroidal cast iron with integrated recesses is used to minimize contact areas between the valve carrier plate and the delivery chamber, reducing heat conduction without additional machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the delivery chamber is in direct contact with the crankcase, then structural simplicity is maintained, but heat transfer from the delivery chamber to the crankcase increases, raising compressor temperature and reducing efficiency
Solution Approach 1:
The crankcase is segmented by introducing recesses that create thermal isolation zones between the delivery chamber and the crankcase body. These recesses break the continuous heat conduction path while maintaining overall structural integrity, effectively reducing heat transfer without requiring complete structural redesign
Solution Approach 2:
Material is extracted from the crankcase structure by forming recesses in the upper portion, removing the thermal conduction path between the delivery chamber and crankcase. This extraction approach reduces heat transfer while maintaining the essential functional structure of the crankcase
2Loss of energy
If recesses are added to the crankcase to reduce heat transfer, then heat dissipation improves, but manufacturing complexity and cost increase due to additional machining operations
Solution Approach 1:
The recesses are formed as integral parts of the crankcase casting process, preparing the thermal isolation structure in advance during manufacturing. This preliminary action eliminates the need for subsequent complex machining operations while ensuring precise geometry and proper positioning of the recesses
Solution Approach 2:
The manufacturing approach changes from traditional machining-based methods to direct casting with integrated recesses. This parameter change in the manufacturing process reduces production complexity and cost while achieving the same heat reduction function
3Loss of energy
If the crankcase is made with integrated recesses through direct casting, then heat transfer is reduced and manufacturing cost is lowered, but manufacturing precision requirements increase to ensure proper recess geometry
Solution Approach 1:
High precision is applied locally only to the recesses in the upper portion of the crankcase where heat transfer occurs, while the rest of the crankcase can be manufactured with standard precision. This localized quality approach ensures proper recess geometry for heat reduction without unnecessarily increasing overall manufacturing precision requirements
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 solution effectively reduces heat transfer between the header and compressor body, maintaining efficiency and cost-effectiveness by utilizing direct casting to create recesses, applicable to both open and semi-hermetic compressors.
Implementation Method 1
heat transfer from the delivery chamber to the crankcase
Implementation Method 2
compresses it into a refrigerant circuit
Implementation Method 3
separate from the refrigerant the lubricating oil, which falls back into the lower portion of the crankcase
Data Source
AI summary
A reciprocating compressor with a head-holding turret in the upper portion of which one or more recesses, open to the outside, are defined, which reduce as much as possible the contact surface with the valve carrier plate above.