WO1993016340A1

WO1993016340A1 - Device and method for improving refrigerating circuit performance

Info

Publication number: WO1993016340A1
Application number: PCT/DE1992/000342
Authority: WO
Inventors: Ulf Greufe
Original assignee: Ulf Greufe
Priority date: 1992-02-11
Filing date: 1992-04-29
Publication date: 1993-08-19
Also published as: AU1795292A; DE4203983A1

Abstract

In conventially driven refrigerating circuits, failures occur particularly during the winter months, since the condenser is designed with too high a rating for this period. In addition, the overall efficiency of the system is relatively low. These problems can be solved by introducing mechanical energy, by means of a pump, into the circuit between the liquid-collection unit and the expansion valve. In order to protect the energy source, a Qmax shutter and a Qmin shutter are fitted. Instead of the pump, the mechanical energy can be supplied in another form, e.g. using the turbocharger principle. The method and device proposed can be used in any piston/cold-water unit or cold-processing plant.

Description

B e s c h r e i b u n

Device and method for improving the performance figure in the refrigerant circuit.

State of the art

The common refrigerant cycle is maintained by the

Compressor, from which the refrigerant flow through the

Condenser, the liquid collector, the expansion valve, the evaporator and back to the compressor.

In systems according to this design, faults occur more frequently, especially in the winter months, because this is precisely the one

Time period of the condenser is too large. In addition, the systems of conventional design have a relatively low overall efficiency with a relatively high power consumption.

The supply of additional mechanical energy is not carried out in the case of piston chillers in all their performance range, nor in cooling process systems.

problem

The invention specified in claim 1 is based on the problem of maintaining the refrigerant circuit, particularly in the cold winter months, and to achieve an increase in the overall efficiency of the system while reducing the power consumption. Invention

This problem is solved with the measures of claim 1 or claim 2.

Advantageous effects of the invention

A modification of the cycle is achieved by installing a refrigerant pump. A Hermetic pump can be installed after your liquid collector. This pump must be arranged in such a way that it is always supplied with sufficient refrigerant. After the refrigerant pump on the pressure side is a Q-max orifice, which must be installed and calculated in such a way that overloading of the stator winding is avoided.

If the expansion valve's performance is throttled, a minimum volume flow that dissipates the heat from the stator must be maintained. The Q-min orifice is intended for this.

By installing the Hermetic pump, there is the possibility that the expansion valve is supplied with sufficient refrigerant with very low condenser pressures. This means that the refrigerant mass flow that is set by the evaporator remains constant. The evaporator becomes the

Refrigerant mass flow is moved in gaseous form via the suction line to the compressor. The compressor compresses the refrigerant gas to a fairly low pressure level, which means that very little compression work is required. The pressure line goes to the condenser, the condenser, which is always too large in the winter months, is now fully usable. Accordingly, performance figures from 7.0.9 can even be driven up to performance figure 10. This means that with 1 KW of power supplied in the compressor, we transport up to 10 KW of cooling power via the evaporator. The refrigerant from the condenser returns to the liquid collector with a very strong subcooling. This has the consequence that - seen from the circular process - quite high enthalpy differences arise. One can generally assume that the annual average

Performance figure improvements can be achieved that are between 5 and 6 in the climate range, which was previously not considered possible.

I understand performance ratio as the relationship between the power consumed by the refrigeration system and the heat transport in the

Evaporator.

The main use of the invention is that the above problems can be solved in all process and air conditioning systems.

Description of a system as an example from practice

A refrigerant pump was used in a customer's system in order to ensure a sufficient refrigerant mass flow through the system with a lower pressure on the condenser side. A Bock motor compressor type DAM 5 / 724-4, refrigerant R22 was used.

The system mentioned above is a system with 2 compressors.

As can be seen from the attached system sketch and the Bock diagram, enormous increases in performance were recorded. The plant has been in operation for almost a year now and works without any problems, with a performance figure increase of

1.72 to 2.75.

A further throttling of the high pressure on the compressor side was not possible in this case, since a failure of the compressor drive due to overload was to be expected. In general, it should be noted that this modification of the cycle process enables a variable number of letters.

So you can generally say that everyone. Deep freeze system, that means any direct evaporation can also be operated with this modified cycle process, which in addition to a trouble-free run in winter, would have the effect of enormous energy cost savings. In addition, there is the possibility of reducing the size of the corresponding systems, that is to say, in other words, the size is also reduced

Machine investment costs etc.

The practical example in numbers

The built-in refrigerant pump has an absorption capacity of 2 KW. The actual state of the system was evaporation temperature: - 10 ° C; the condensation temperature was at 53 ° C; the

Pressure ratio of the plant was approx. 11; the net cooling capacity was 37 KW.

After the modification, the evaporation temperature was + - 0 C; the condensing temperature at 32 ° C; the net cooling capacity at 83 KW; at lower power consumption of the compressor.

Performance figure comparison in the modified cycle

Cooling capacity old = 38 KW cooling capacity new = 88 KW power consumption old = 22 KW power consumption new = 32 KW Service figure old

Cooling capacity old 38 KW 1, 72

Power consumption 22 KW old

Service figure new

Cooling capacity new 88 KW 2, 75

Power consumption 32 KW new

New power consumption = power consumption (compressor + condenser fan + refrigerant pump = 29, 5 KW + 1, 0 KW + 1, 5 KW.

Further education of the achievement

The supply of mechanical energy can be done by the usual methods such as Electric motor or turbocharger.

Presentation of the invention

The example of an execution is based on the representation of the

Refrigerant circuit. It is clearly shown that the corresponding pump must be installed after the liquid collector below its level. Furthermore, they are

Places clearly indicated where the Q-min screen or the Q-max screen are to be installed.

In addition, a diagram is attached, which shows a comparison of the old with the new internal efficiency. Another diagram compares the old delivery level with the new one.

Finally, two sketches are included, from which you can see the cooling capacity achieved by installing the motor compressor.

Claims

P a t e n t a n s r u c h e

Closed refrigerant circuit, starting from the Verdicliter, via the condenser, the liquid collector, via the

Expansion valve, the evaporator back to the compressor, characterized in that between the liquid collector and the expansion valve additional energy is introduced into the cycle by a pump. The overload of this pump is prevented by a Q-max orifice, while when the expansion valve is throttled, a minimum volume flow is guaranteed by installing a Q-min-BleTTde.

2. Mechanical Snergfe according to claim 1

^' Characterized in that it can be supplied by means of an electric motor or according to the de turbocharger principle.