METHOD FOR OPERATING AN AIR CONDITIONING SYSTEM FOR A VEHICLE, AND AIR CONDITIONING SYSTEM ARRANGEMENT

Abstract

A method for operating an air conditioning system for a vehicle for transporting persons. The air conditioning system, depending on the current number of passengers in a passenger compartment of the vehicle (level of occupation), controls a fresh air volume flow to be introduced into the passenger compartment from outside the vehicle in order to maintain a predefined minimum ambient air quality. The air conditioning system determines a total water mass flow, which is currently produced by the passengers in the passenger compartment, on the basis of air-conditioning measurement values and a current value for at least one operating parameter of the air conditioning system. From the total water mass flow and a predefined value for a water mass flow produced by a single passenger, the system determines the current number of passengers in the passenger compartment. There is also described an air conditioning arrangement for carrying out the method.

Claims

1-8. (canceled)

9. A method for operating an air conditioning system for a vehicle for transporting persons, the method which comprises: determining a total water mass flow that is currently being produced by passengers in a passenger compartment of the vehicle on a basis of air-conditioning measurement values and a current value for at least one operating parameter of the air conditioning system; determining, from the total water mass flow and a predefined value for a water mass flow produced by one passenger, a current number of passengers in the passenger compartment; and controlling, with the air conditioning system, a fresh air volume flow to be introduced into the passenger compartment from outside the vehicle in order to maintain a predefined minimum compartment air quality in dependence on the current number of passengers in the passenger compartment of the vehicle (level of occupation).

10. The method according to claim 9, wherein the air conditioning system determines the current number of passengers in the passenger compartment by way of the following equation: $n=\frac{V_{\mathrm{fr}}.Math.\left({\rho }_i.Math.x_i-{\rho }_{\mathrm{fr}}.Math.x_{\mathrm{fr}}\right)}{{\stackrel{.}{m}}_p}$ where: n is the number of passengers; V.sub.fr is the fresh air volume flow [m.sup.3/h]; ρ.sub.i is a density of compartment air [kg/m.sup.3]; χ.sub.i is a specific humidity of the compartment air [kg/kg]; ρ.sub.fr is a density of the fresh air [kg/m.sup.3]; χ.sub.fr is a specific humidity of the fresh air [kg/kg]; and rh.sub.p is the mass flow of water produced by one person [kg/h].

11. The method according to claim 10, wherein the air conditioning system has signal connections to respective sensors for an exterior temperature and an exterior humidity of the fresh air, an interior or recirculated air temperature and an interior or recirculated air humidity of the compartment air and the step of calculating the number of passengers currently in the passenger compartment comprises: using, as a value for the at least one operating parameter of the air conditioning system, a current set value of the air conditioning control system or of the train control system for the fresh air volume flow in accordance with the current operating state of the air conditioning system.

12. The method according to claim 11, which comprises measuring an exterior humidity with a humidity sensor arranged in a region of at least one fresh air intake of the vehicle.

13. An air conditioning arrangement for a vehicle for transporting persons, the air conditioning arrangement comprising: an air conditioning system configured to control, in dependence on a current number of passengers in a passenger compartment of the vehicle (level of occupation), a fresh air volume flow to be introduced into the passenger compartment from outside the vehicle in order to maintain a predefined minimum compartment air quality; said air conditioning system having signal connections to respective sensors or an exterior temperature of the fresh air, an internal or recirculated air temperature, and an internal or recirculated air humidity of a compartment air; a sensor disposed to sense an exterior humidity of the fresh air; and the air conditioning arrangement being configured to determine, based on measurement values supplied by said sensors and of a current value for at least one operating parameter of the air conditioning system, a total water mass flow that is currently being produced by the passengers currently in the passenger compartment, and to determine, from the total water mass flow and a predefined value for a water mass flow produced by a single passenger, the current number of passengers in the passenger compartment.

14. The air conditioning arrangement according to claim 13, wherein said air conditioning system is configured to determine the current number of passengers in the passenger compartment by way of the following equation: $n=\frac{V_{\mathrm{fr}}.Math.\left({\rho }_i.Math.x_i-{\rho }_{\mathrm{fr}}.Math.x_{\mathrm{fr}}\right)}{{\stackrel{.}{m}}_p}$ where: n is the number of passengers; V.sub.fr is the fresh air volume flow [m.sup.3/h]; ρ.sub.i is a density of compartment air [kg/m.sup.3]; χ.sub.i is a specific humidity of the compartment air [kg/kg]; ρ.sub.fr is a density of the fresh air [kg/m.sup.3]; χ.sub.fr is a specific humidity of the fresh air [kg/kg]; and rh.sub.p is the mass flow of water produced by one person [kg/h].

15. The air conditioning arrangement according to claim 14, wherein for a calculation of a current number of passengers in the vehicle, a current set value of the air conditioning control system or of the train control system for the fresh air volume flow according to the current operating state of the air conditioning system is stored as a value for the at least one operating parameter.

16. The air conditioning arrangement according to claim 13, wherein said sensor for measuring the exterior humidity is disposed in a region of at least one fresh air intake of the vehicle.

Description

[0027] An exemplary embodiment of the invention is explained in greater detail below with reference to the drawing. The single FIGURE shows a schematic illustration of an air conditioning arrangement of a rail vehicle.

[0028] The FIGURE shows a longitudinal section of a car body of a rail vehicle, which is used as an example of a vehicle for transporting people. A passenger compartment 1 of the rail vehicle is supplied with conditioned supply air by means of an air conditioning system 2. A current mode of operation of the air conditioning system depends on how many passengers are currently located in the passenger compartment 1, i.e. what level of occupation is currently to be used as a basis for the passenger compartment. Proceeding from this, the air conditioning system 2 has the task of controlling a fresh air volume flow to be introduced into the passenger compartment 1 from outside the vehicle in order to maintain a predefined minimum compartment air quality, and to do this as economically as possible.

[0029] Information on current climatic conditions is made available to the air conditioning system 2 via a number of sensors. A temperature sensor 3 and a humidity sensor 4 for determining the specific humidity of the compartment air Xi are provided for the interior air which is located in the passenger compartment 1.

[0030] In order to supply the passenger compartment 1 with conditioned supply air, the air conditioning system 2 delivers fresh air by way of a fresh air fan (not shown), which introduces fresh air into the passenger compartment 1 from outside the vehicle through a fresh air opening 5. In addition, the air conditioning system 2 controls an exhaust air fan (not shown), which conveys room air originating from the passenger compartment 1 through an exhaust air opening 6 to the outside of the vehicle.

[0031] In order to determine the climatic parameters of the fresh air to be introduced, the air conditioning arrangement comprises an external temperature sensor 7 and a humidity sensor 8, which is arranged in the region of the inlet opening for fresh air and by means of which the specific humidity of the fresh air χ.sub.fr can be determined.

[0032] All the sensors, namely the sensor for the internal temperature 3, the internal humidity 4, the external temperature 7 and the external humidity 8, have signal connections to the air conditioning system 2. This system evaluates the measurement values supplied by the sensors 3, 4, 7, 8 for the various measured variables in order to determine a current number of passengers located in the passenger compartment 1. This is accomplished by means of the following equation:

[00002]$n=\frac{V_{\mathrm{fr}}.Math.\left({\rho }_i.Math.x_i-{\rho }_{\mathrm{fr}}.Math.x_{\mathrm{fr}}\right)}{{\stackrel{.}{m}}_p}$ [0033] n: number of passengers [0034] V.sub.fr fresh air volume flow [m.sup.3/h] [0035] ρ.sub.i: density of compartment air [kg/m.sup.3] [0036] χ.sub.i: specific humidity of the compartment air [kg/kg] [0037] ρ.sub.fr: density of the fresh air [kg/m.sup.3] [0038] χ.sub.fr: specific humidity of the fresh air [kg/kg] [0039] rh.sub.p: mass flow of water produced by one person [kg/h].

[0040] It is apparent that the fresh air volume flow V.sub.fr is included in the determination of the number n of passengers currently located in the passenger compartment 1. For this purpose, a current set value of the air conditioning control system or of the vehicle control system is preferably used for the fresh air volume flow V.sub.fr. Furthermore, the equation comprises the water mass flow rh.sub.p produced by one person. This is stored as a constant value for the calculation of the number n and is obtained from the quotient of the latent heat emission of the human person and the specific enthalpy of evaporation of the water. Here, the latent heat emission of the human person, normally clothed and seated, can be taken from air conditioning comfort standards for rail vehicles (EN 14813, EN 14750 or EN 13129). In contrast, the specific enthalpy of evaporation of the water is a quantity which can be looked up in tables.

[0041] It should be emphasized that, in order to carry out the method explained above for determining the number n of passengers currently located in the passenger compartment 1, known air conditioning arrangements of vehicles, in particular rail vehicles, can in many cases be retrofitted in a simple manner. Frequently, only the humidity sensor 8 for the fresh air which is introduced into the passenger compartment 1 from the outside will have to be added.

[0042] It should also be noted that the interior sensor 3 and the humidity sensor 4 can be replaced by a temperature sensor and a humidity sensor which are located in a recirculated-air air conditioning duct of the vehicle if such a duct is provided in the vehicle. A recirculated-air air conditioning duct carries air which originates from the passenger compartment 1 but does not leave the vehicle as exhaust air, instead being mixed in an air distribution box with fresh air sucked in from the outside and returned to the passenger compartment 1, for example.