Refrigeration appliance having parallel evaporators and operating method therefor
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Solution Overview
Problem
Refrigeration appliances with parallel evaporators face inefficiencies due to varying refrigerant quantities in the circuit, leading to inadequate cooling in warmer compartments, especially with fluctuating ambient temperatures and refrigerant distribution.
Innovation Solution
A method involving a compressor, condenser, and shut-off valve, where the compressor operates with the shut-off valve closed to recirculate refrigerant from the colder compartment to the condenser, estimating the mass flow rate based on compressor power and temperature sensors to ensure a consistent refrigerant supply to the warmer compartment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If parallel evaporators are used with shut-off valves to enable selective cooling of storage compartments, then cooling selectivity is improved, but device complexity increases due to additional valves and control mechanisms
Solution Approach 1:
The patent combines multiple evaporators (first evaporator for warm compartment, second evaporator for cold compartment) into a single parallel configuration within the refrigerant circuit, allowing both evaporators to operate simultaneously or selectively without requiring complex individual control valves for each evaporator. The merging of evaporators in parallel enables cooling selectivity through simpler means.
Solution Approach 2:
The refrigerant circuit is designed with a universal parallel evaporator system that can serve multiple storage compartments (warm and cold) simultaneously. The system can adaptively distribute refrigerant to different evaporators based on cooling demands, making the refrigerant circuit multi-functional without requiring dedicated valve assemblies for each compartment.
2Quantity of substance
If shut-off valve is closed to recirculate refrigerant from cold compartment evaporator to condenser, then adequate refrigerant quantity for warm compartment cooling is improved, but refrigerant circulation efficiency deteriorates due to extended recirculation time
Solution Approach 1:
The control unit performs preliminary assessment by estimating the mass flow rate through the compressor and calculating the required recirculation time before actually closing the shut-off valve. This preliminary calculation ensures that the recirculation process is initiated at the optimal moment and lasts for the precise duration needed to accumulate adequate refrigerant quantity, preventing both premature and excessive recirculation.
Solution Approach 2:
The system implements feedback control by continuously monitoring compressor operation parameters, estimating mass flow rate in real-time, and using this information to dynamically adjust the recirculation duration. The control unit calculates the required recirculation time based on current system state, creating a closed-loop control that optimizes refrigerant accumulation while minimizing unnecessary recirculation time.
3Quantity of substance
If compressor operates with closed shut-off valve to accumulate refrigerant, then refrigerant distribution to warm compartment is improved, but energy consumption increases due to extended compressor operation
Solution Approach 1:
The control unit performs preliminary calculation of the exact recirculation duration needed based on estimated mass flow rate before initiating compressor operation with closed shut-off valve. This ensures the compressor runs for the minimum necessary time to accumulate adequate refrigerant, avoiding prolonged operation and excessive energy consumption.
Solution Approach 2:
The system dynamically adjusts the recirculation duration based on real-time estimation of mass flow rate through the compressor. Rather than using fixed recirculation times, the control unit calculates and implements variable recirculation durations that adapt to changing system conditions, optimizing the balance between refrigerant accumulation and energy consumption.
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 ensures a reliable quantity of circulating refrigerant for efficient operation of the warmer evaporator, preventing over-recirculation and maintaining optimal refrigerant distribution, thereby enhancing cooling efficiency and reducing operational inefficiencies.
Implementation Method 1
a compressor (4), in particular a speed-regulated compressor (4), to compress a refrigerant (R134a)
Implementation Method 2
a condenser (5) connected to a pressure connection (16) of the compressor (4)
Implementation Method 3
a first evaporator (8) for cooling the warm storage compartment (1), a second evaporator (10) for cooling the cold storage compartment (2)
Data Source
AI summary
A refrigeration appliance includes at least one warm storage compartment and one cold storage compartment and a refrigeration device having at least two mutually parallel evaporators connected in series with a compressor, a condenser, and a shut-off valve between the condenser and evaporators in a refrigerant circuit so that each evaporator cools one storage compartment. An operating method for the refrigeration appliance includes the steps a) deciding whether a need for cooling has newly occurred in the warm storage compartment, and, if so, b) operating the compressor while the shut-off valve is closed to cause refrigerant to back up in the condenser, c) opening the shut-off valve and supplying the evaporator of the warm storage compartment with the backed up refrigerant. In step b) the mass flow rate through the compressor is estimated and the time for performing step c) is determined by using the estimated mass flow rate.