Absorption Heat Pump Evaporator Defrost via Hot Refrigerant Bypass
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Solution Overview
Problem
Absorption heat pumps experience reduced efficiency when ambient air temperature drops below 0°C due to frost or ice formation on the outdoor air heat exchanger, which acts as a thermal insulator, significantly reducing heat absorption and supply.
Innovation Solution
A hot gas line is branched from the refrigerant vapor line, bypassing the condenser and expansion valve, to directly supply hot refrigerant to the evaporator, allowing for defrosting by heating the evaporator and outdoor air heat exchanger above normal operating temperatures, and a method is implemented to control the flow of refrigerant vapor using a defrost valve, along with adjustments to the fan and brine pump speeds to enhance defrosting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the absorption heat pump operates in cold ambient air (below 0°C), then heat absorption from ambient air is required, but frost or ice forms on the outdoor air heat exchanger acting as a thermal insulator, significantly reducing heat absorption efficiency
Solution Approach 1:
The invention utilizes the hot refrigerant vapor that would normally be wasted or require cooling in the condenser and converts this thermal energy into a beneficial defrosting resource. By diverting the hot refrigerant vapor through the hot gas line directly to the evaporator, the harmful ice buildup is melted using otherwise unused thermal energy, thereby converting a harmful factor (ice formation) into a beneficial effect (defrosting) without additional energy input.
Solution Approach 2:
The invention extracts the hot refrigerant vapor from the main refrigeration cycle before it enters the condenser by providing a bypass line (hot gas line) that branches off from the refrigerant vapor line. This extraction allows the hot vapor to be directed specifically to the evaporator for defrosting purposes, separating the defrosting function from the normal cooling cycle and enabling independent control of the defrosting process.
2Reliability
If a conventional defrosting method using the condenser is used, then the evaporator can be heated, but the refrigerant is cooled in the condenser reducing the efficiency of the defrosting process
Solution Approach 1:
The invention extracts the hot refrigerant vapor from the main refrigeration cycle before it enters the condenser by providing a bypass line (hot gas line) that branches off from the refrigerant vapor line. This extraction allows the hot vapor to be directed specifically to the evaporator for defrosting purposes, separating the defrosting function from the normal cooling cycle and enabling independent control of the defrosting process.
Solution Approach 2:
The invention utilizes the hot refrigerant vapor that would normally be wasted or require cooling in the condenser and converts this thermal energy into a beneficial defrosting resource. By diverting the hot refrigerant vapor through the hot gas line directly to the evaporator, the harmful ice buildup is melted using otherwise unused thermal energy, thereby converting a harmful factor (ice formation) into a beneficial effect (defrosting) without additional energy input.
3Reliability
If the hot gas line is used to supply hot refrigerant to the evaporator, then the evaporator can be heated above normal operating temperature for defrosting, but additional control components (defrost valve) are required
Solution Approach 1:
The defrost valve integrated into the hot gas line serves multiple functions: it controls the defrosting process by regulating hot refrigerant flow to the evaporator, and it can be controlled based on various parameters (temperature, time, pressure) to optimize defrosting efficiency. This single component provides both flow control and process regulation, reducing the need for additional separate control mechanisms.
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 solution effectively defrosts the outdoor air heat exchanger, maintaining heat absorption efficiency by preventing ice buildup and ensuring continuous operation even in cold conditions, thereby enhancing the overall performance of the absorption heat pump.
Implementation Method 1
the evaporator is heated above its normal operating temperature... the outdoor air heat exchanger is also heated above its normal operating temperature
Implementation Method 2
This defrosting process removes the insulating layer of ice that hinders the heat absorption
Implementation Method 3
extracts heat from the ambient air and transfers it to a consumer... the evaporator exchanges heat with a fluid circuit, which in turn incorporates an outdoor air heat exchanger
Implementation Method 4
a condenser branch, which passes through the condenser... the condensation heat from the refrigerant condensing in the condenser branch can be absorbed
Data Source
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AI summary
The present invention relates to an absorption heat pump having a generator (20) which is designed to receive a solution containing a refrigerant, a heat source which is designed to heat the generator (20) in order to expel a refrigerant vapor from the solution, and a condenser for Cooling of the refrigerant vapor against a consumer. An expansion valve (40) is provided, which is designed to expand the refrigerant fluid, and an evaporator (50) for at least partially evaporating the expanded refrigerant fluid against a medium which is connected to at least one absorber (60, 60A, 60B), the for absorbing the expanded refrigerant fluid by a low-refrigerant solution. According to the invention, a hot gas line (100) is provided, which branches off from a line (32) for refrigerant vapor upstream of the condenser (30) and is in fluid communication with the evaporator (50) in such a way that it connects the condenser (30) and the expansion valve (40). bypasses, wherein a defrost valve (102) is provided in the hot gas line, by means of which the flow of refrigerant vapor through the hot gas line can be controlled. The invention also relates to a method for operating an absorption heat pump in a cyclic cycle, in which, in defrosting operation, the refrigerant vapor taken from the generator is branched off at least partially upstream of the condenser (30) and sent to the evaporator (50), bypassing the condenser (30) and expansion valve (40 ) is supplied to heat the evaporator.