Shared-Casing Screw Expander Compressor for Seal-Free Refrigeration
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Solution Overview
Problem
Existing cooling devices for vehicles require shaft seal devices to prevent heat medium leakage between the expander and compressor, leading to potential failures and increased maintenance costs due to the need for equal condensation temperatures and pressures in refrigeration and Rankine cycles.
Innovation Solution
A refrigerator design where the exhaust side of the screw expander is connected to the discharge side of the screw compressor within a common casing, eliminating the need for shaft seal devices by ensuring equal exhaust and discharge pressures, and optionally incorporating a generator to convert surplus energy into electricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shaft seal devices are provided on the exhaust side of the expander and on the suction side of the compressor to prevent heat medium leakage, then the sealing reliability is improved, but the device complexity and maintenance needs increase
Solution Approach 1:
The patent merges the exhaust side of the expander and the discharge side of the compressor into a common space within the casing. By equalizing the pressure in this common space with the condenser pressure, the system eliminates the need for separate shaft seal devices on both the expander and compressor, thereby reducing device complexity while maintaining sealing reliability through pressure equilibrium.
Solution Approach 2:
The patent extracts and eliminates the shaft seal devices from the system by redesigning the pressure distribution. Instead of using shaft seals to prevent leakage, the system takes out the need for sealing by creating a common pressure space, thereby simplifying the overall device structure.
2Reliability
If shaft seal devices are provided to prevent heat medium leakage, then the heat medium retention is improved, but the maintenance frequency increases
Solution Approach 1:
By merging the exhaust and discharge sides into a common space and equalizing pressures, the system reduces the number of sealing points that require maintenance. The heat medium retention is maintained through pressure equilibrium rather than mechanical seals, significantly reducing maintenance frequency.
Solution Approach 2:
The system uses the pressure differential and flow dynamics to automatically maintain heat medium retention without active sealing components. The common space design allows the system to self-regulate pressure distribution, eliminating the need for maintenance of shaft seal devices.
3Adaptability or versatility
If the condensation temperature and pressure of the refrigeration cycle are equal to those of the Rankine cycle, then the system integration is improved, but the need for shaft seal devices increases
Solution Approach 1:
The patent merges the Rankine cycle and refrigeration cycle into a partially shared system where the condenser is common to both cycles. By equalizing the condensation pressure and creating a common space for the expander exhaust and compressor discharge, the system achieves high integration while eliminating the need for shaft seal devices through pressure equilibrium.
Solution Approach 2:
The condenser serves dual functions for both the Rankine cycle and refrigeration cycle, and the common space between expander and compressor serves multiple purposes: pressure equalization, heat medium flow path, and elimination of sealing requirements. This multi-functionality reduces overall device complexity while maintaining system integration.
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 configuration simplifies the structure, reduces maintenance needs, and allows for efficient energy recovery and power generation without shaft seals, resulting in a cost-effective and reliable cooling system.
Implementation Method 1
a high-temperature evaporator for vaporizing a heat medium
Implementation Method 2
a condenser to which the heat medium exhausted from the screw expander is introduced
Implementation Method 3
an expansion valve for decompressing the remaining portion of the heat medium liquefied in the condenser
Implementation Method 4
a screw compressor for compressing the heat medium vaporized by the low-temperature evaporator
Data Source
AI summary
A refrigerator of the present invention includes a Rankine cycle heat engine and a refrigeration cycle heat engine which share a condenser, and drives a compressor of the refrigeration cycle by an expander of the Rankine cycle. A screw expander and a screw compressor are set up within a common casing, and the exhaust side of a rotating shaft of the screw expander is connected to the discharge side of a rotating shaft of the screw compressor. Preferably, an intermediate space in which an exhaust passage of the screw expander and a discharge passage of the screw compressor are merged together and connected to a condenser, and a coupling which connects the rotating shaft of the screw expander to the rotating shaft of the screw compressor is housed is formed within the casing.