Test bypass for a cooling apparatus, having a liquid vessel with a variable pressure level

Abstract

The invention relates to a method for simulation of an isothermal and non-isothermal heating load introduced by a consuming device (V) into a process medium (M) of a cooling apparatus (1), said simulation being by means of a test bypass (2); and the invention further relates to such a test bypass (2), and a cooling apparatus having such a test bypass.

Claims

1. A method for simulating isothermal and non-isothermal heating loads imposed by a consuming device (V) in a process medium (M) of a cooling apparatus (1), said method comprising: providing a test bypass having a flow connection between a forward flow (A) of the cooling apparatus (1) and a return flow (B) of the cooling apparatus (1), wherein the test bypass (2) further comprises at least one regulating valve (CV1, CV2), a first heater (H1) for introducing an isothermal heating load, a vessel (G), and a second heater (H2) for introducing an non-isothermal load, passing the process medium (M) from the forward flow (A) through the test bypass (2) to the return flow (B), introducing a predefined isothermal heating load by means of the first heater (H1) into the process medium (M) and introducing a predefined non-isothermal heating load by means of the second heater (H2) into the process medium (M), establishing a process pressure (p4), by means of the at least one regulating valve (CV1, CV2), in the vessel (G) into which the isothermal heating load is introduced, so that in the vessel (G) a constant level (LI4) of a liquid phase (F) of the process medium (M) is maintained, measuring at a point (Z1, Z2, Z6, Z7) in the test bypass (2) a state of the process medium (M), and using the measured state of the isothermal heating load at said point (Z1, Z2, Z6, Z7) and the process pressure (p4) at said point (Z1, Z2, Z6, Z7), calculating the mass flow (m) of the process medium (M) at said point.

2. The method according to claim 1, wherein the measuring of the state of the process medium (M) at said point (Z1, Z2, Z6, Z7) comprises measuring the temperature of the process medium (M) at said point and measuring the pressure of the process medium (M) at said point.

3. The method according to claim 1, further comprising measuring at a second point in the test bypass (2) the pressure or temperature of the process medium (M), and by means of the pressure or temperature measured at said second point, the calculated mass flow (m), and the non-isothermal heating load, determining a state of the process medium (M) at the second point in the test bypass (2).

4. The method according to claim 1, wherein the first heater (H1) is disposed upstream of the vessel (G); and the second heater (H2) is disposed downstream of the vessel (G).

5. The method according to claim 1, wherein the at least one regulating valve (CV1) is disposed upstream of the first heater (H1).

6. The method according to claim 1, wherein the at least one regulating valve (CV2) is disposed downstream of the second heater (H2).

7. The method according to claim 5, wherein the test bypass (2) has a second regulating valve (CV2), for adjusting the pressure (p4) in the vessel (G), wherein the second regulating valve (CV2) is disposed downstream of the second heater (H2).

8. The method according to claim 7, wherein the point (Z1, Z2, Z6, Z7) is one of the following points of the test bypass (2): a point (Z1) disposed upstream of the at least one regulating valve (CV1) and/or upstream of the first heater (H1); a point (Z2) disposed downstream of the at least one regulating valve (CV1) and upstream of the first heater (H1); a point (Z7) disposed downstream of the at least one regulating valve (CV2) and/or downstream of the second heater (H2); a point (Z6) disposed upstream of the at least one regulating valve (CV2) and downstream of the second heater (H2); a point (Z7) disposed downstream of the second regulating valve (CV2) and downstream of the second heater (H2); and a point (Z6) disposed upstream of the second regulating valve (CV2) and downstream of the second heater (H2).

9. The method according to claim 1, wherein the first heater (H1) is disposed in the vessel (G); and the second heater (H2) is disposed downstream of the vessel (G).

10. The method according to claim 1, wherein the at least one regulating valve (CV1) is disposed downstream of the first heater (H1) and upstream of the vessel (G).

11. The method according to claim 1, wherein the at least one regulating valve (CV2) is disposed downstream of the vessel (G) and upstream of the second heater (H2).

12. The method according to claim 5, wherein the test bypass (2) has a second regulating valve (CV2), for adjusting the pressure (p4) in the vessel (G), wherein the second regulating valve (CV2) is disposed downstream of the vessel (G) and upstream of the second heater (H2).

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Additional features and advantages of the invention will be described hereinbelow with the aid of an exemplary embodiment of the invention and the accompanying drawing.

(2) FIG. 1 is a schematic representation of a test bypass in a cooling apparatus according to an embodiment of the invention.

(3) FIG. 1 illustrates a cooling apparatus 1 wherein a combination of an isothermal and a non-isothermal heating load is to be simulated, which load may be produced, e.g., by a consuming device V which is also illustrated in FIG. 1. To simulate the heating loads, according to the invention a test bypass 2 is employed which provides a flow connection between the forward flow A of the cooling apparatus 1 and the return flow B of the cooling apparatus 1.

(4) The test bypass 2, in which the process medium M is passed around or past the consuming device V (so as to bypass the consuming device V) and is sent to the return flow B, has a first heating means H1 which introduces the determined isothermal load Q.sub.2-3 into the process. Downstream of the first heating means H1, a vessel G for accommodating the process medium M is provided, and downstream of vessel G a second heating means H2 is provided. With the aid of a regulating valve CV1 or CV2, disposed downstream of the first heating means H1 (regulating valve CV1) or downstream of the second heating means H2 (regulating valve CV2), the process pressure p4 is established (adjusted) in the liquid vessel G, where the isothermal load Q.sub.2-3 is introduced.

(5) With the aid of process status measuring means at point Z1 (measuring e.g. temperature and pressure, by suitable means 4), and with knowledge of the load Q.sub.2-3 which is applied, and the pressure p4, and taking into account the energy balance, the mass flow m at point Z1 can be determined. With this it is assumed that a quasi-static process is in effect, and thus that the level-measuring means LI4 in the liquid vessel G shows a constant level. In this connection, the thermodynamic constraint is employed that saturated vapor at the process pressure p4 is flowing at points Z3 and Z5. Once the mass flow m is known, then the status at each status point in the test bypass 2 can be determined, via the known heating load Q.sub.5-6, if a pressure measurement is available for each position (e.g. [via] means 5). In general, means for measuring pressure and/or temperature may be provided at each of the points of the test bypass 2 (e.g. points Z1 to Z7).

(6) In the quasi-static case under consideration (with a constant level of the liquid phase in the vessel G), then the following is true for the derivatives of the mass flow with respect to time, at points Z1 to Z7:
dm/dt(1)=dm/dt(2)=dm/dt(3)=dm/dt(5)=dm/dt(6)=dm/dt(7)
LI4=constant.

(7) Further, for the specific enthalpies at the individual points Z1 to Z7:
h.sub.1=h.sub.2
h.sub.3=h.sub.5=h.sub.saturated vapor (at p4)
h.sub.6=h.sub.7; and
Q.sub.2-3=dM/dt*(h.sub.3h.sub.2)=dm/dt*(h.sub.saturated vapor (at p.sub.4)h.sub.2)
Q.sub.5-6=dM/dt*(h.sub.6h.sub.5)=dm/dt*(h.sub.6h.sub.saturated vapor (at p.sub.4)).

(8) Here, h.sub.x represents the specific enthalpy at point x of the test bypass 2, p.sub.x represents the static pressure at point x, Qx.sub.x+1 represents the heating load which is introduced to the process between point x and point x+1, and LI4 represents the measured level in the liquid vessel G.

(9) Using the above equations, the desired quantities may be readily calculated.

(10) Thus, with the aid of the heat introduced, Q.sub.2-3, and the known pressure p4 at the state point Z4 and [sic] the known state point Z1, one can determine the mass flow.

(11) The following are known:
h.sub.1(p1,T1)=h.sub.2,
h.sub.5=h.sub.saturated vapor(p4).

(12) The following are to be determined:
dm/dt=Q.sub.2-3/(h.sub.5h.sub.2)=Q.sub.2-3/(h.sub.saturated vapor(p4)h.sub.1(p1,T1)).

(13) Using the inventive arrangement and method, it is possible, advantageously, to minimize the required number of measurements and the global tolerance of the measurements. The information obtained with the arrangement is utilized such that saturated vapor flows upstream and downstream of the liquid vessel G.

(14) Also, with the introduction of an additional regulating valve CV2 (e.g. downstream of the second heating means H2), any pressure between p1 and p7 in the vessel may be set, with p1 being the pressure at Z1 and p7 being the pressure at Z7, and thereby isothermal loads of different modes can be simulated at the corresponding different temperature levels. Further, there is a clear difference between the isothermal load Q.sub.2-3 (from the heating means H1) and the isothermal load Q.sub.5-6 (from the heating means H2), which can be advantageous during the acceptance test, and for regulation of the apparatus. The heating means H1 and H2 may be, e.g., electric heating means.

(15) Instead of measurements being made at the state point Z1, they may be made at another point (at state point Z2, Z6, or Z7), or the mass flow m may be measured and then values at other state points may be derived from it.

(16) Instead of pressure measurements, temperature measurements may be made, from which values at any point may be obtained for the exact state point.

(17) In alternative embodiments (not shown) the first heating means H1 may disposed upstream of the regulating valve CV1 or in the liquid vessel G. Alternatively or additionally, the second heating means H2 may be disposed downstream of the second regulating valve CV2 (not shown in FIGURE).

LIST OF REFERENCE NUMERALS

(18) TABLE-US-00001 1 Cooling apparatus 2 Test bypass 4 Means for measuring a state of the process medium 5 Means for measuring the pressure or temperature CV1, CV2 Regulating valve G Vessel. H1 First heating means H2 Second heating means LI4 Level of the process medium in the vessel M Process medium Z1 to Z7 Points of the test bypass A Inflow (forward flow) B Return flow V Consuming device