PWM Multi-Evaporator Refrigeration for Mixed-Pressure Cooling
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Solution Overview
Problem
Conventional refrigeration systems with multiple evaporators face inefficiencies due to the need for complex control strategies and valve systems to manage different inlet pressures from multiple evaporators, leading to energy wastage and reduced compressor efficiency.
Innovation Solution
A refrigeration system employing a single linear compressor and multiple evaporators connected in parallel, utilizing a pulse-width modulation (PWM) switch valve to manage refrigerant fluid pressure, allowing all evaporators to operate simultaneously at different pressure levels and frequencies, thereby optimizing compressor efficiency and reducing system losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If multiple evaporators operate simultaneously at different pressure levels, then compressor efficiency is improved and energy consumption is reduced, but complex valve systems and control strategies are required to manage different inlet pressures
Solution Approach 1:
The system divides the refrigerant flow management into separate parallel evaporator circuits, each operating independently at its own pressure level. This segmentation allows each evaporator to be optimized for its specific thermal load without requiring pressure equalization across all evaporators, thereby improving compressor efficiency while managing complexity through modular design.
Solution Approach 2:
A common suction manifold acts as an intermediary component that receives refrigerant from multiple evaporators operating at different pressure levels and delivers a unified suction flow to the compressor. This intermediary structure enables pressure differentiation across evaporators while maintaining a single efficient compression stage, resolving the contradiction between operational efficiency and system complexity.
2Device complexity
If a single compressor is used to serve multiple evaporators, then system cost and complexity are reduced, but the compressor must handle varying inlet pressures from different evaporators
Solution Approach 1:
The common suction manifold creates an equipotential zone that equalizes pressure at the compressor inlet, ensuring that despite variations in evaporator outlet pressures, the compressor receives a stable and uniform suction pressure. This maintains reliable and stable compressor operation while allowing the evaporators to operate independently at different pressure levels.
3Adaptability or versatility
If evaporators operate at different pressure levels, then flexibility in responding to changing thermal loads is improved, but energy wastage occurs without proper pressure management
Solution Approach 1:
The system dynamically adjusts refrigerant flow distribution to each evaporator based on its instantaneous thermal load requirements. Each evaporator can independently modulate its refrigerant flow rate and pressure level to match its cooling demand, maximizing adaptability to changing thermal loads while the common suction manifold ensures efficient energy utilization by the compressor.
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 enables efficient operation of multiple evaporators at varying pressures, reducing energy consumption and eliminating the need for complex control systems, while maintaining high compressor efficiency and flexibility in responding to changing thermal loads.
Implementation Method 1
utilizing a pulse-width modulation (PWM) switch valve to manage refrigerant fluid pressure
Implementation Method 2
a linear compressor that is activated and deactivated by a pulse width modulation switching device
Implementation Method 3
a condenser operably coupled to the compressor outlet and configured to receive refrigerant fluid from the compressor
Implementation Method 4
at least two evaporators operably connected in parallel with one another with at least one evaporator associated with the refrigerator compartment that operates at a first refrigerant fluid pressure and with at least one other evaporator associated with the freezer compartment that operates at a second refrigerant fluid pressure
Data Source
AI summary
A refrigeration system including a condenser; a (single) linear compressor that is activated and deactivated by a pulse width modulation switching device; a pulse width modulation refrigerant flow switch; at least two evaporators operably connected in parallel with one another with at least one evaporator associated with the refrigerator compartment that operates at a first refrigerant fluid pressure and with at least one other evaporator associated with the freezer compartment that operates at a second refrigerant fluid pressure; and a plurality of refrigerant fluid conduits operably connecting the condenser, the linear compressor and the evaporators into a refrigerant fluid flow circuit and such that the evaporators are capable of running simultaneously at different pressure levels and refrigerant flows from the evaporators, to the pulse width modulation refrigerant flow switch and through the pulse width modulation refrigerant flow switch.