Cold storage systems
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Solution Overview
Problem
Existing cold storage systems face challenges in maintaining ultra-low temperatures efficiently and reliably, particularly for degradable materials like life science products, due to the extreme temperature differences between the interior and ambient environments, which can lead to operational inefficiencies and ice formation on evaporator coils.
Innovation Solution
The system employs a refrigeration module with a cascade refrigeration system and forced air convection, utilizing a blower to direct airflow through the chamber, and enhanced door seals to maintain temperatures below −50°C, while incorporating a defrost mechanism to prevent ice buildup on evaporator coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the evaporator is positioned vertically higher than the chamber to enable forced air convection cooling, then the cooling efficiency is improved, but the risk of ice formation on the evaporator coils increases
Solution Approach 1:
The system implements periodic defrost cycles where the evaporator is heated at regular intervals to melt accumulated ice. The controller activates the defrost mechanism (heating element or reverse cycle) when ice buildup is detected or after a predetermined time period, then returns to normal cooling operation, creating a periodic alternation between cooling and defrost phases.
Solution Approach 2:
The system converts the harmful effect of cold air pooling above the chamber into a beneficial circulation pattern. The blower actively forces the cold air that would naturally accumulate at the top to circulate back down through the chamber, transforming the potential harm (ice formation from cold pooling) into improved cooling distribution and efficiency.
2Ease of manufacture
If the door seal uses a single continuous door stop to simplify the structure, then the manufacturing complexity is reduced, but the sealing reliability deteriorates due to thermal contraction
Solution Approach 1:
The door stop is divided into multiple separate segments rather than being a single continuous piece. These segments are positioned at different locations around the door frame and are thermally isolated from each other, allowing each segment to contract independently in response to temperature changes while collectively maintaining the door seal's integrity.
Solution Approach 2:
The door seal incorporates a flexible sealing material as an intermediary element between the door stop segments and the door. This flexible material compensates for minor misalignments and gaps created by thermal contraction of the rigid door stop segments, ensuring continuous sealing contact despite dimensional changes.
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 system achieves consistent and reliable ultra-low temperatures, enhances operational efficiency, and prevents ice formation, ensuring the integrity of stored products by maintaining desired temperature conditions.
Implementation Method 1
a blower that is configured to generate an airflow that is in thermal communication with the evaporator, and ducting that is configured to circulate the airflow between the chamber and the evaporator
Implementation Method 2
an evaporator positioned vertically higher than the chamber, a blower that is configured to generate an airflow that is in thermal communication with the evaporator
Implementation Method 3
a second door stop parallel to and discontinuous from the first door stop such that the first door stop and the second door stop are configured to thermally contract independently of one another
Data Source
AI summary
An embodiment of a cold storage system includes a housing further including a chamber having a front opening closeable by an outer door and a back wall opposite the front opening, one or more outlets defined in the back wall, and one or more inlets defined in the chamber more proximate the front opening than the back wall. In addition, the cold storage system includes a refrigeration module operably coupled to the chamber. The refrigeration module includes an evaporator positioned vertically higher than the chamber, a blower configured to generate an airflow that is in thermal communication with the evaporator, and ducting configured to circulate the airflow between the chamber and the evaporator via the inlets and the outlets such that the airflow is directed through the outlets into the chamber and then from the chamber into the inlets to cool the chamber.