Cryogenic Heat Exchanger Warm-Up Using Diverted Refrigerant Flow

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Solution Overview

Problem

Very low temperature refrigeration systems take excessively long to warm up due to insulation, making it difficult to service and diagnose issues such as leaks, which results in prolonged downtime and reduced productivity.

Innovation Solution

A method is introduced to rapidly warm the heat exchanger array by diverting refrigerant flow from the compressor to specific points in the heat exchanger array, using warmer refrigerant and buffer valves to manage refrigerant mass flow, allowing for quicker temperature changes and balancing pressures within the system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the heat exchanger array is well insulated to minimize parasitic heat losses, then energy efficiency is improved, but the warm-up time during servicing increases significantly

Engineering Contradiction:

Improveparasitic heat lossesVSAvoidwarm-up time

Core Design Contradiction:

Loss of energyVSLoss of time

Solution Approach 1:

The refrigerant flow path is segmented into multiple circuits, allowing selective diversion of refrigerant through different pathways. During normal operation, refrigerant flows through the cooling circuit, but during servicing, the flow is diverted through the heat exchanger array via alternative pathways, enabling rapid warming without compromising the insulation's energy-saving function

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system pre-positions warmer refrigerant in the refrigeration circuit, ready to be diverted to the heat exchanger array when warming is needed. This preliminary preparation of warm refrigerant allows immediate action when servicing is required, reducing warm-up time from days to hours while maintaining insulation integrity during normal operation

Inventive Principle:

Principle #10Preliminary action

2Loss of time

If refrigerant flow is diverted to warm the heat exchanger array rapidly, then warm-up time is reduced, but excessive refrigerant mass flow through the compressor may occur

Engineering Contradiction:

Improvewarm-up timeVSAvoidcompressor overload

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The refrigerant flow distribution is made dynamic and adjustable through control valves. The system can adaptively regulate the amount of refrigerant diverted to the heat exchanger array based on real-time conditions, preventing compressor overload while achieving rapid warming. The valves dynamically balance the refrigerant flow between the cooling circuit and the warming pathway

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

Control valves serve as intermediaries between the compressor and the heat exchanger array, mediating the refrigerant flow. These valves prevent excessive mass flow to the compressor by regulating and throttling the refrigerant, while still allowing sufficient flow to reach the heat exchanger array for rapid warming

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of repair

If the refrigeration system is shut down for servicing, then diagnostic work can be performed, but the equipment remains unavailable for productive operations during the warm-up period

Engineering Contradiction:

Improveservice accessVSAvoidoperational availability

Core Design Contradiction:

Ease of repairVSProductivity

Solution Approach 1:

The system performs preliminary warming action using diverted refrigerant flow before servicing begins. By pre-warming the heat exchanger array while the system is still operational or during the initial shutdown phase, the actual servicing can begin sooner, reducing the total downtime and improving equipment availability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The refrigeration system maintains continuous useful action by diverting refrigerant flow to warm the heat exchanger array during the shutdown period. Instead of complete inactivity, the system continuously circulates refrigerant through the warming pathway, making productive use of the shutdown time and reducing the overall service interruption duration

Inventive Principle:

Principle #20Continuity of useful action

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 method significantly reduces the warm-up time from days to less than an hour, enabling faster service and diagnosis, and allows for balancing pressures within minutes, thus improving operational efficiency and reducing downtime.

Implementation Method 1

diverting at least a portion of refrigerant flow in the refrigeration system away from a refrigerant flow circuit used during very low temperature cooling operation of the refrigeration system, to effect warming of at least a portion of the heat exchanger array

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentUS10228167B2Systems and methods for warming a cryogenic heat exchanger array, for compact and efficient refrigeration, and for adaptive power management

Publication Date: 2019.03.12 EDWARDS VACUUM LLC

AI summary

In accordance with an embodiment of the invention, there is provided a method of warming a heat exchanger array of a very low temperature refrigeration system, the method comprising diverting at least a portion of refrigerant flow in the refrigeration system away from a refrigerant flow circuit used during very low temperature cooling operation of the refrigeration system, to effect warming of at least a portion of the heat exchanger array; and while diverting the at least a portion of refrigerant flow, preventing excessive refrigerant mass flow through a compressor of the refrigeration system.