Auto-defrost system in actively cooled tote
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Solution Overview
Problem
The accumulation of frost on the accept heat exchanger in temperature-controlled totes significantly reduces the efficiency of the refrigeration system, leading to an inability to maintain set-point temperature even at maximum power input.
Innovation Solution
An automatic defrosting system is implemented, which includes determining the need for a defrost cycle, deactivating the cooling system, activating a defrost heater to melt frost, and then reactivating the cooling system once the frost has melted and dripped into a collection tray.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cooling system operates continuously to maintain set-point temperature, then cooling performance is improved, but frost accumulates on the heat exchanger reducing efficiency
Solution Approach 1:
The system implements periodic defrost cycles where the cooling system is temporarily suspended and a defrost heater is activated to melt accumulated frost on the heat exchanger. This periodic intervention prevents complete frost-up while allowing continuous overall operation, resolving the contradiction between maintaining cooling performance and preventing frost accumulation.
2Object-generated harmful factors
If a defrost heater is activated to melt frost, then frost accumulation is reduced, but energy consumption increases
Solution Approach 1:
The control system monitors heat exchanger temperature and frost accumulation levels to determine when defrost cycles are necessary. By using feedback from temperature sensors and operational data, the system activates the defrost heater only when needed rather than continuously, reducing unnecessary energy consumption while effectively managing frost accumulation.
Solution Approach 2:
The system changes operational parameters by temporarily suspending the cooling system and activating heating during defrost cycles. This parameter switching allows the heat exchanger temperature to rise above freezing to melt frost, then returns to normal cooling operation, efficiently managing frost while minimizing energy waste.
3Object-generated harmful factors
If manual defrosting is performed, then frost removal is achieved, but operational disruptions increase
Solution Approach 1:
The system performs automatic defrosting through integrated control that monitors frost accumulation and activates the defrost heater without manual intervention. The control system autonomously manages the defrost cycles, eliminating the need for manual defrosting operations and reducing operational disruptions while effectively removing frost accumulation.
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 automatic defrosting system maintains less than 50 grams of frost on the heat exchanger, preventing complete frost-up and maintaining cooling performance, while also automating the defrosting process to minimize disruptions to normal operations.
Implementation Method 1
activating a defrost heater to melt frost
Implementation Method 2
a heat exchanger, referred to as an 'accept', to transfer heat from the air to be conditioned
Implementation Method 3
moisture will naturally condense and then freeze on the accept heat exchanger
Implementation Method 4
moisture will naturally condense and then freeze on the accept heat exchanger
Data Source
AI summary
Systems and methods for automatic defrosting of an actively cooled tote are provided. In some embodiments, a method of operating an actively cooled container includes: determining to initiate a defrost cycle for the actively cooled container; deactivating a cooling system of the actively cooled container; activating a defrost heater of the actively cooled container; determining to deactivate the defrost heater of the actively cooled container; setting the defrost heater to maintain a temperature of a thermal accept system at a threshold; waiting a set duration of time to allow for melted frost to drip into a collection tray; and activating the cooling system of the actively cooled container.