Solar-Powered Cooling Device with Time-Dependent Temperature Control
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Solution Overview
Problem
Photovoltaic-powered cooling devices struggle to maintain a consistent temperature range of +2 °C to +8 °C without sunlight, leading to limited storage capacity and maintenance issues, and existing solutions require additional heating and complex components.
Innovation Solution
A cooling device with a primary and secondary cooling circuit, a hysteresis-controlled compressor, and an independent energy supply via a DC converter and capacitors to maintain temperature stability and maximize energy use, allowing for continuous operation and complete freezing of cooling elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the compressor runs continuously to generate sufficient cooling capacity, then the cooling performance is improved, but the energy consumption increases significantly
Solution Approach 1:
The control interrupts the cooling process periodically by switching the compressor on and off based on the comparison between actual temperature and time-dependent temperature comparison values. This allows the system to accumulate cooling capacity during operation while limiting energy consumption over the evaluation period.
Solution Approach 2:
The control pre-calculates and stores time-dependent temperature comparison values that represent acceptable temperature trajectories. These pre-defined reference values guide the compressor operation in advance, allowing the system to plan cooling actions ahead of time based on expected temperature evolution.
2Temperature
If the temperature comparison value is reduced to further cool the cooling space, then the cooling capacity is improved, but the risk of damaging medical products increases
Solution Approach 1:
The control continuously measures the actual temperature in the cooling space and compares it with time-dependent reference values. Based on this feedback, the control dynamically adjusts whether to activate the compressor, ensuring that cooling actions are taken only when appropriate and stopping before temperatures become harmful to medical products.
Solution Approach 2:
The system uses time-dependent temperature comparison values that change throughout the evaluation period. These reference values are reduced in steps to allow progressive cooling while maintaining a safety margin, enabling the system to adapt the cooling target temperature dynamically based on the elapsed time and current thermal state.
3Stability of the object's composition
If a heater is added to prevent the cold room temperature from falling below 0 °C, then the temperature stability is improved, but the device complexity increases
Solution Approach 1:
The control pre-defines time-dependent temperature comparison values that inherently prevent the temperature from falling below safe thresholds. By planning the cooling trajectory in advance and using these reference values as stop criteria, the system avoids over-cooling without requiring additional heating components to compensate.
4Quantity of substance
If the storage capacity for medical products is increased, then the utility is improved, but the thermal mass required to store cold increases
Solution Approach 1:
The control operates the compressor continuously during the evaluation period whenever the actual temperature is below the time-dependent comparison value, maximizing the accumulation of cooling capacity. This continuous useful action allows larger storage capacities to be supported by efficiently utilizing the available energy supply throughout the entire evaluation period.
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
Ensures consistent temperature control around the setpoint, maximizes storage capacity without additional heating, and simplifies maintenance by using energy efficiently and independently of sunlight availability.
Implementation Method 1
an independent energy supply via a DC converter and capacitors
Implementation Method 2
an independent energy supply via a DC converter and capacitors
Implementation Method 3
at least one compressor
Implementation Method 4
at least one condenser
Implementation Method 5
at least one evaporator
Implementation Method 6
A cooling device with a primary and secondary cooling circuit, a hysteresis-controlled compressor
Data Source
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AI summary
The invention relates to a cooling device, comprising at least one regeneratively operated primary cooling circuit, in particular a solar-powered cooling circuit, wherein the cooling circuit has at least one compressor, at least one condenser, at least one evaporator, at least one cooling space, at least one temperature sensor for measuring the cooling space temperature (Tair) in the cooling space, and a controller. A desired temperature value (SET) of the cooling space and a comparison temperature value (TSET) can be stored in the controller. The invention is characterised in that the cooling of the cooling space can be interrupted by the controller and the comparison temperature value (TSET) can be changed by the controller depending upon the time and/or the cooling space temperature (Tair). The invention further relates to a method for controlling a cooling device, which is characterised in that the comparison temperature value (TSET) corresponds to the desired temperature value (SET) when the controller is switched on, and the cooling of the cooling space is interrupted when the actual cooling space temperature (Tair) has reached the comparison temperature value (TSET). In this connection, the comparison temperature value (TSET) is reduced after a predetermined time period (t0) by a stored correction value (dSET), so long as the actual cooling space temperature (Tair) has not reached the comparison temperature value (TSET) within the predetermined time period (to).