Cooling device for electrical and/or electronic component elements producing lost heat and a procedure for operating such

A cooling system for cooling at least one semiconductor component, including a convection heat exchanger thermally coupled to the component and a refrigeration cycle thermally coupled to the heat exchanger and including a compressor, a condenser, a collector, an expansion valve and an evaporator. The evaporator is coupled in series with the heat exchanger to form a coolant cycle for recooling of the coolant. At least one fan is provided for forcibly ventilating the convection heat exchanger. The condenser of the refrigeration cycle is installed in the heat exchanger whereby the fan serves also to cool the condenser. A coolant, in particular trifluortrichlorethane (C.sub.2 F.sub.3 Cl.sub.3), having a boiling point below the wall temperature of the semiconductor component being cooled is used.

FIELD OF THE INVENTION 
This invention refers to a cooling device for electrical and/or electronic 
component elements producing lost heat, in particular for electrical 
semiconductor component elements, with a coolant cycle in which there is a 
forced air ventilation thermal exchange mechanism for the recooling of the 
coolant. 
This invention also refers to a procedure for operating the above-described 
cooling device. 
DESCRIPTION OF THE PRIOR ART 
Water or oil functions as the coolant for direct fluid cooling of the 
semiconductor component elements in a familiar cooling device of the 
above-mentioned type (Siemens Magazine 44 (1970), Vol. 1, pages 39 to 43). 
In this way the heated coolant fluid can be recooled by means of a forced 
air ventilation thermal exchange mechanism or by means of a second fluid 
cycle. Water cooling is more effective than oil cooling; yet even 
chemically pure water tries to introduce ions from the surrounding 
substances into the solution so that an exchange of ions is necessary in 
order to maintain a certain insulating capacity of the water. 
When cooling electrical semiconductor elements, for example current 
director valves, with coolant cycles and forced air ventilated thermal 
exchange mechanisms, water and oil are commonly used as primary coolants 
but with certain disadvantage, namely low insulating capacity along with 
practically unavoidable impurities in water and a reduction in the 
insulating capacity in conductors outside of the coolant due to the 
collection of dust at oil leakage sites. Other, essentially suitable 
coolants would require an inefficient enlargement of the thermal exchange 
mechanism. 
Furthermore, water freezes at below 273 K. In case of any leakage, 
insulating transformer oil induces the collection of dust and can, 
therefore, lead to a negative influence on the electrical voltage 
strength. This danger also exists when silicon oil is used. 
SUMMARY OF THE INVENTION 
Accordingly, one object of this invention is to provide a novel cooling 
device of the above-mentioned type in such a way that inert-like fluids, 
for example derivatives of methane or of ethane in appropriate compounds, 
can be used as coolants without necessitating an enlargement in the 
thermal exchange mechanism. 
This object is achieved in accordance with the discovery by providing a 
novel cooling system in which, the coolant cycle flows through the 
vaporizer of a coolant cycle system. Therefore, a portion of the heat can 
be advantageously derived, as is common, from the forced air ventilated 
thermal exchange mechanism and the other part from the cooling system. 
The invention solves the problems of the prior art by means of a secondary 
coolant cycle with a vaporizer, through which the primary coolant cycle is 
channeled, in addition to the forced air ventilated thermal exchange unit. 
Thereby, a part of the released heat is removed from the thermal exchange 
unit and the rest is removed by the vaporizer and the secondary coolant 
cycle. That is when using specially suitable primary coolants such as 
inert-like fluids, an enlargement of the thermal exchange mechanism can be 
avoided. For this purpose, the condenser of the secondary cycle is 
connected to the thermal exchange unit. 
Preferably, the condenser of the coolant cycle system is built into the 
forced air ventilated thermal exchange mechanism of the coolant cycle with 
which it does not have to work as hard and smaller dimensions of the 
thermal exchange mechanism are possible. 
Another object of the invention is to provide a method for operating the 
cooling device with which the cooling process can be designed especially 
efficient. 
This object is achieved by using a coolant, the boiling point of which is 
somewhat lower than the contact temperature of the element to be cooled 
for the purpose of combined convection and boiling cooling, and channeling 
a portion of the lost heat to the vaporizer of the cooling system only 
above a pre-determined surrounding temperature. 
The heat is derived primarily by means of convection in the 
above-described, familiar fluid cooling process. Yet in the selection of 
coolants, the boiling point of which is somewhat lower than the contact 
temperature of the element to be cooled, as proposed by the discovery, 
heat is also derived from boiling along with convection in some areas so 
that a higher degree of effectivity is achieved. 
For this purpose C.sub.2 F.sub.3 Cl.sub.3 is chosen as a coolant. On the 
basis of the temperature conditions which, for example, exist in the 
coolant containers that can be used for fluid cooling of electrical 
semiconductor component elements in accordance to DE-OS No. 26 40 000, 
essentially a coolant with a boiling point between 328 K. and 333 K. would 
be desirable. The C.sub.2 F.sub.3 Cl.sub.3 compound (type 113) with a 
boiling point of 320.6 K. provides the best approximation of this 
temperature range at the present time. Nevertheless, because of the 
relatively low boiling point of this compound, the temperature gradient 
for recooling (liquification) of the coolant is very low. At a surrounding 
temperature of 313 K., for example, it is only 7.6 K. so that essentially 
an even larger thermal exchange mechanism would be necessary. On the other 
hand, when cooling directional current circuits, considerable losses in 
power of up to a few hundred kW have to be carried off. A cooling system 
having to process the entire capacity would be too voluminous and would 
have a very low degree of efficiency. Therefore dividing up the lost power 
to the forced air ventilated thermal exchange mechanism and the cooling 
system provides an optimal solution. With this it is possible to construct 
the thermal exchange mechanism at a size corresponding to purely 
conventional functioning thermal exchange mechanisms. Furthermore, 
depending upon the capacity of the cooling system, one is capable of 
lowering the coolant temperature below that of the surrounding air with 
which one then can more effectively cool the component elements producing 
lost heat.

DESCRIPTION OF THE PRFERRED EMBODIMENTS 
Referring now to the drawing, the example therein shown refers to the 
cooling of a current directer (1). The coolant cycle, when viewed in the 
direction of the current, includes piping (2), a thermal exchange 
mechanism (3) attached to a ventilator (4), piping (5), a vaporizer (6), 
piping (7), a pump (8), and a reverse flow pipe (9) leading, for example, 
to the cooling containers of the semiconductor component elements of the 
current directer (1). 
The vaporizer (6) is a part of a cooling cycle system which contains (when 
viewed from the vaporizer (6) in the direction of the current): a 
compressor (10), a condenser (11), a collecter (12), and an expansion 
valve (13). 
The cooling device funtions in the following way: 
The coolant is partially vaporized at the surfaces giving off heat, for 
example, from the cooling containers of the electrical semiconductor 
component elements of the current directer (1). The partially gaseous, 
partially fluid coolant is channeled through the piping (2) to the thermal 
exchange unit (3) where a larger part of the heat is channeled off to the 
surroundings by means of convection caused by the fan (4) although no 
complete liquification of the coolant actually occurs. This occurs only if 
the coolant flows through the vaporizer (6) of the cooling system through 
piping (5). The temperature of the coolant can be more or less below its 
boiling point. Then the coolant is transported again to the current 
directer for taking on heat through piping (7), the pump (8), and piping 
(9). The cooling system consists of common parts and functions in a 
familiar way. For this purpose the condenser (11) is built into the 
thermal exchange mechanism (3) of the coolant cycle because it can 
function at higher temperatures. With this practically no ventilator power 
is saved--only portions of the degree of effectivity--but there are 
considerable savings in the volume of these parts and in the costs 
necessary for this. 
Advantageously, the coolant cycle can function at relatively low pressures 
resulting mainly from the losses in flow because the gas pressure of the 
preferred coolant C.sub.2 F.sub.3 Cl, (Type 113) increases by less than 1 
bar at the temperature cited. 
The use of coolants, primarily of type 113, for cooling electronic 
components is an essentially known process (Scientific report of 
AEG-Telefunken 51 (1978) 1, pages 30-39; Bulletin ASE/UCS 68 (Dec. 17, 
1977) 24, pages 1314-1317). From these works it can be seen that because 
of the low temperature gradients between the surrounding air and the 
boiling point of the coolant, a coolant water cycle is used. The expanded 
version, that can then occasion recooling of the water with the 
surrounding air, is only relevant if the surrounding temperatures are low 
enough. Yet this explanation is not comprehensible; for if such low 
temperatures exist, one can recool the coolant with the surrounding air 
directly as well and thereby work with better degrees of efficiency. 
The combination of the thermal exchange unit (3) and a sequentially 
positioned vaporizer (6), as proposed by the invention, functions with 
surprising effectivity at a very low degree of complexity. 
The cooling device also allows for the removal of the total lost capacity 
from the thermal exchange unit so that a portion of the lost heat is 
channeled to the vaporizer of the cooling system only when the 
surroundings are above a predetermined temperature and then removed from 
this. One can design the thermal exchange mechanism (3) in correspondance 
with the mean annual temperature if, at this temperature, a sufficient 
temperature gradient results for removing the entire lost capacity. As 
long as the pre-determined surrounding temperature, being somewhat above 
the mean annual temperature, is not exceeded, then the cooling system can 
be turned off so that for a large part of the year there can be recooling 
with a better degree of efficiency. 
The cooling system, on the one hand, can be included for cooling the 
control electronics as well as for cooling the current directer (1) at 
very hot room temperatures and, on the other hand, it can also be used for 
air conditioning rooms occupied by human beings. 
Finally, the cooling system not only allows for the possible use of a 
coolant the boiling point of which is somewhat lower than the contact 
temperature of the component element to be cooled in accordance with the 
preferred method but rather also for the use of a coolant with a higher 
boiling point for which the principle of dividing the lost capacity to the 
thermal exchange unit (3) and the vaporizer (6) is used at surrounding 
temperatures occurring in all cases. 
Obviously, numerous modifications and variations of the present invention 
are possible in light of the above teachings. It is therefore to be 
understood that within the scope of the appended claims, the invention may 
be practiced otherwise than as specifically described herein.