WO2016015768A1

WO2016015768A1 - Refrigeration appliance having freezer evaporator defrost circuit

Info

Publication number: WO2016015768A1
Application number: PCT/EP2014/066477
Authority: WO
Inventors: Tugba SARICAY; Turgay Ercan
Original assignee: Arcelik Anonim Sirketi
Priority date: 2014-07-31
Filing date: 2014-07-31
Publication date: 2016-02-04
Also published as: EP3175184B1; TR201808809T4; EP3175184A1

Abstract

The present invention relates to a refrigeration appliance having at least one fresh food refrigeration compartment and at least one freezer compartment, the refrigeration appliance having a refrigeration and defrost circuit (1) comprising a compressor (2) for compressing a refrigerant to a high temperature and a high pressure, a condenser coil (3) in connection with the compressor (2) and in which the refrigerant is condensable into liquid, a cooling coil (5) in connection with the condenser coil (3) through a first refrigerant expansion element (6) and a freezing coil (8) in connection with the condenser coil (3) through a second refrigerant expansion element (7).

Description

REFRIGERATION APPLIANCE HAVING FREEZER EVAPORATOR DEFROST CIRCUIT

The present invention relates to a refrigeration appliance provided with an improved defrost mechanism.

It is known that in a conventional vapor compression system, a closed refrigerant circuit is provided having a compressible refrigerant which flows through a compressor, a condenser, a refrigerant expansion element and an evaporator. A refrigerant compressed in the compressor is typically condensed into a liquid by the condenser, and then evaporated in the evaporator.

The condenser effects transfer of thermal energy from the compressed refrigerant to the ambient air and the evaporator transfers thermal energy from the ambient air in the refrigeration compartment to the compressed refrigerant. The compressed refrigerant in the refrigerant circuit is in superheated vapor phase while leaving the compressor. It transforms into the liquid-vapor state in the condenser and then into the liquid state enroute to the refrigerant expansion element. The refrigerant changes to liquid-vapor phase in the refrigerant expansion element while the pressure thereof is being reduced.

Condensation forms due to vapor in the air around the cooling coil having a surface temperature below the freezing point of water. While the cooling coil i.e. the evaporator gradually collects frost to the extent that this condensation freezes, ice builds up on the evaporator surface. Ice being a relatively good heat insulator, ice and frost accumulation on the evaporator surface should be prevented and the build-up of frost should be removed to maintain the ability of the evaporator to transfer thermal energy as well as to ensure the efficient operation of the refrigeration appliance.

In this regard, refrigeration appliances are usually equipped with a system for automatically defrosting the cooling coil at specified intervals so that the ice accumulated on the cooling coil surface is melted and the resultant water is drained away. Such a system may provide that feeding of the compressed refrigerant to the evaporator is temporarily interrupted and a hot refrigerant is directed to the evaporator to defrost the ice collected on the surfaces thereof. The flow of hot refrigerant to the cooling coil is subsequently stopped and the circulation of compressed refrigerant is continued. To address the ice accumulation problem, a defrost heater can alternatively be employed to thaw or defrost the ice formed. However, such a unit not only requires electric power expenditure but also causes reduced efficiency due to temperature fluctuations.

A plurality of hot gas defrost systems having structural variations are present in the state of the art. Among others, one of the prior art disclosures in the technical field of the present invention may be referred to as EP1334321, which discloses a defrosting method for a refrigeration appliance having multiple refrigeration compartments, specifically a fresh food compartment and a freezer compartment, which comprises a fresh food evaporator for cooling the fresh food compartment and a freezer evaporator for cooling the freezer compartment. The fresh food evaporator is composed of two separate evaporators namely a first sub-evaporator and a second sub-evaporator. Sub-evaporators are arranged in parallel and both of the sub-evaporators are used sequentially for cooling the fresh-food compartment. This enables continuous cooling of the fresh food compartment and defrosting of the fresh food evaporator concurrently.

The present invention is devised under the recognition that an improved defrost system specifically dedicated to a freezer evaporator and effecting the defrost operation thereof in a substantially accelerated manner remains a need.

The present invention provides a refrigeration appliance having a freezer evaporator defrost system by which the ice formed on the freezer cooling coil surface of the appliance can be efficiently and rapidly thawed.

The present invention therefore provides a refrigeration appliance having a freezer cooling coil defrost system as provided by the characterizing features defined in Claim 1.

Primary object of the present invention is to provide an improved freezer cooling coil defrost system in a refrigeration appliance.

The present invention proposes a refrigeration appliance having one fresh food compartment along with a freezer compartment. A compressor, a condenser coil, a cooling coil in association with said fresh food compartment and a freezing coil in association with said freezer compartment are provided.

A switching valve is provided to be located directly before the freezing coil such that it allows selective fluid communication to the freezing coil from a cooling, defrost or freezing circuit lines. The switching valve is both in connection with the cooling coil and a refrigerant expansion element in separate lines. It is in direct communication with the compressor to transfer a hot refrigerant directly to the freezing coil through the defrost circuit line.

The switching valve, while completing the freezing circuit from the condenser, through the refrigerant expansion element and the freezing coil to the compressor, also provides a return line for the refrigerant flowing through the cooling coil.

Accompanying drawings are given solely for the purpose of exemplifying a refrigeration appliance having a refrigeration and defrost circuit, whose advantages over prior art were outlined above and will be explained in brief hereinafter.

The drawings are not meant to delimit the scope of protection as identified in the claims nor should they be referred to alone in an effort to interpret the scope identified in said claims without recourse to the technical disclosure in the description of the present invention.

Fig. 1 demonstrates a general schematic diagram of a conventional refrigeration and defrost circuit.

Fig. 2 demonstrates a general schematic diagram of a refrigeration and defrost circuit according to the present invention.

Fig. 3 demonstrates a general schematic diagram of a refrigeration and defrost circuit according to the present invention.

The following numerals are assigned to different parts demonstrated in the drawings:

Refrigeration and defrost circuit
Compressor
Condenser coil
Switching valve
Cooling coil
First refrigerant expansion element
Second refrigerant expansion element
Freezing coil
Cooling circuit line
Defrost circuit line
Freezing circuit line
Compressor return line
Defrost heater

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The present invention relates to a refrigeration appliance with a fresh food refrigeration compartment and a freezer compartment, said appliance further having a compressor (2) compressing a refrigerant to a high temperature and a high pressure, the compressor (2) typically having a suction inlet and a high pressure outlet. A condenser coil (3) in connection with the high-pressure outlet of the compressor (2) is provided to condensate the refrigerant into a liquid.

Fig. 1 demonstrates a conventional refrigeration and defrost circuit having operably connected thereto in serial order a compressor (2), a condenser coil (3), a freezing coil (8), i.e. the freezing evaporator and a cooling coil (5), i.e. the fresh food evaporator. A defrosting system in the form of a defrost heater (13) typically provides defrosting of the freezing coil (8) at specified intervals in an automated manner so that the ice accumulated on the surfaces of the freezing coil (8) is melted, the ice formed is thawed. The freezing coil (8) evaporating the refrigerant has an inlet connected to a first refrigerant expansion element (6) and an outlet connected to the cooling coil (5). Said cooling coil (5) is in turn connected to the compressor (2) through the suction inlet thereof. The cooling and freezing coils (5, 8) may typically have a refrigerant flowing pipe and a multitude of plate-shaped fins extending in parallel in an equidistant manner.

Fig. 2 demonstrates another refrigeration and defrost circuit having operably connected thereto in serial order a compressor (2), a condenser coil (3), a cooling coil (5) and a freezing coil (8). A switching valve (4) connects the outlet of the condenser coil (3) selectively to a first refrigerant expansion element (6) or to a second refrigerant expansion element (7). Said switching valve (4) therefore controls the flowing direction of the refrigerant through a cooling circuit line (9) or a freezing circuit line (11).

According to the structure shown in Fig. 2, the compressor (2) circulates a compressible refrigerant to the condenser coil (3) in which the refrigerant is condensed into liquid due to transfer of thermal energy from the compressed refrigerant to the ambient air. Through the cooling circuit line (9), the refrigerant flows through the first refrigerant expansion element (6) typically in the form of a capillary tube, changing to liquid-vapor phase while its pressure is reduced. The refrigerant is then evaporated in the cooling coil (5) due to heat exchange with the air in the fresh food compartment and returns to the compressor (2) through a compressor return line (12) passing through the freezing coil (8).

Alternatively, the compressor (2) circulates the compressible refrigerant to the condenser coil (3), flowing through the freezing circuit line (11) and through the second refrigerant expansion element (7) to the freezer coil (8). Alternatively, the compressor (2) may circulate hot refrigerant to the freezing coil (8) through a defrost circuit line (10) such that the freezing coil (8) is defrosted.

According to the present invention, an improved defrost system is provided such that the defrost operation of the freezer coil (8) is effected in a substantially accelerated manner. In order for obtaining an accelerated result, a switching valve (4) is situated right before the freezing coil (8) and in connection with the cooling coil (5) and the second refrigerant expansion element (7) in separate lines. The switching valve (4) being in direct communication with the compressor (2) can transfer the hot refrigerant directly to the freezing coil (8) through a defrost circuit line (10).

To this end, the switching valve’s (4) outlets serve as inlets in the manner that the three outlets thereof fluidly communicate with the cooling, defrost and freezing circuit lines (9, 10, 11). Therefore, the structural configuration of the defrost circuit line (10) in accordance with the present invention is advantageous in that the hot gas is not circulated to the condenser coil (3) first, since the compressor (2) directly communicates with the freezing coil (8) by means of the switching valve (4). The switching valve (4), on the other hand, can communicate with the second refrigerant expansion element (7) and the cooling coil (5) in separate lines so as to complete the freezing circuit line (11) for the freezing coil (8) and to simultaneously form a return line (12) for the refrigerant flowing through the cooling coil (5).

According to an aspect of the present invention, the switching valve (4) is an electrically operated valve realized in the form of a solenoid valve. These units are three-way solenoid valves having selectively opening outlets to the cooling, defrost or freezing circuit lines (9, 10 and 11) in accordance with the operation mode of the refrigeration and defrost circuit (1). More specifically, the switching valve (4) selectively allows refrigerant flow in the cooling circuit line (9), the defrost circuit line (10) or the freezing circuit line (11).

In a nutshell, the present invention proposes a refrigeration appliance having at least one fresh food refrigeration compartment and at least one freezer compartment, the refrigeration appliance having a refrigeration and defrost circuit (1) comprising a compressor (2) for compressing a refrigerant to a high temperature and a high pressure, a condenser coil (3) in connection with the compressor (2) and in which the refrigerant is condensable into liquid, a cooling coil (5) in connection with the condenser coil (3) through a first refrigerant expansion element (6) and a freezing coil (8) in connection with the condenser coil (3) through a second refrigerant expansion element (7).

In one embodiment of the present invention, a switching valve (4) is situated directly before the freezing coil (8) and in connection with the cooling coil (5) and the second refrigerant expansion element (7) in separate lines.

In a further embodiment of the present invention, the switching valve (4) is in direct communication with the compressor (2) to transfer a hot refrigerant directly to the freezing coil (8) through a defrost circuit line (10).

In a still further embodiment of the present invention, the switching valve (4) fluidly communicates with the cooling coil (5) in a cooling circuit line (9) and with the second refrigerant expansion element (7) in a freezing circuit line (11).

In a yet still further embodiment of the present invention, the switching valve (4) completes the freezing circuit line (11) for the freezing coil (8) and simultaneously forms a return line (12) for the refrigerant flowing through the cooling coil (5).

In a yet still further embodiment of the present invention, the switching valve’s (4) outlets serve as inlets in the manner that the three outlets thereof fluidly communicate with the cooling, defrost and freezing circuit lines (9, 10, 11).

The present invention therefore affords a refrigeration and defrost circuit (1) by which the ice accumulation problem is addressed so as to efficiently thaw the ice formed on the freezing coil (8) surface in an accelerated manner. More specifically, the present invention ensures that the compressor (2) directly communicates with the freezing coil (8) by means of the switching valve (4), the latter being in fluid communication with the second refrigerant expansion element (7) and the cooling coil (5) in separate lines so as to complete the freezing circuit line (11) for the freezing coil (8) and simultaneously form the return line (12) for the refrigerant flowing through the cooling coil (5).

Claims

A refrigeration appliance having at least one fresh food refrigeration compartment and at least one freezer compartment, the refrigeration appliance having a refrigeration and defrost circuit (1) comprising a compressor (2) for compressing a refrigerant to a high temperature and a high pressure, a condenser coil (3) in connection with the compressor (2) and in which the refrigerant is condensable into liquid, a cooling coil (5) in connection with the condenser coil (3) through a first refrigerant expansion element (6) and a freezing coil (8) in connection with said condenser coil (3) through a second refrigerant expansion element (7), characterized in that

a switching valve (4) is situated directly before the freezing coil (3) and in connection with the cooling coil (5) and said second refrigerant expansion element (7) in separate lines.
A refrigeration appliance as in Claim 1, characterized in that the switching valve (4) is in direct communication with the compressor (2) to transfer a hot refrigerant directly to the freezing coil (8) through a defrost circuit line (10).
A refrigeration appliance as in Claim 1 or 2, characterized in that the switching valve (4) fluidly communicates with the cooling coil (5) in a cooling circuit line (9) and with the second refrigerant expansion element (7) in a freezing circuit line (11).
A refrigeration appliance as in Claim 3, characterized in that the switching valve (4) completes the freezing circuit line (11) for the freezing coil (8) and simultaneously forms a return line (12) for the refrigerant flowing through the cooling coil (5).
A refrigeration appliance as in Claim 3 or 4, characterized in that the switching valve’s (4) outlets serve as inlets in the manner that the three outlets thereof fluidly communicate with the cooling, defrost and freezing circuit lines (9, 10, 11).