MX2014003708A - Device for measuring the thermal properties of constructive systems. - Google Patents

Abstract

The invention consists in a machine for measuring variables, which allows the thermal conductivity to be measured in constructive systems. The invention is useful for measuring samples of 1.20 m wide with a height of 2.10 m and 600 kg of weight such as a real scale wall. The invention includes a transporting cart where the samples are manufactured and a cart system for introducing the sample in the samples cabinet between the cold and hot plate. Once the sample is inside, the machine is turned ON so that the cold and hot parts work together creating a temperature differential at the sides of the wall. The system for measuring the temperature in the surfaces of the sample is based on thermocouples, which are integrated to the cold and hot plates; they have a system of a retractable spring for being brought into complete contact with the surface of the wall, which may have irregularities, since they are constructive walls. The cart system allows the sample to be constructed outside the machine so as to be introduced in the porta-samples. A system of inner carts in the machine is useful for moving the hot plate when the sample is inside, sealing the plates to the sample with a programmed electro-pneumatic system.

Description

DEVICE FOR MEASURING THE THERMAL PROPERTIES OF SYSTEMS CONSTRUCTIVES TECHNICAL FIELD OF THE INVENTION The present invention belongs to the technical field of engineering, specifically to the heat transfer as it deals with a device for measuring the coefficient of thermal transfer in construction walls.

BACKGROUND In the construction engineering, it is often required to know the thermal properties of construction systems, specifically the thermal conductivity to evaluate the behavior of these elements and thus complement the information for the application of the Mexican regulations in the evaluation of the thermal resistance of elements construction, based on the NMX-C-460, as well as the application of NOM-020 for the evaluation of energy efficiency in residential buildings.

Currently, there are several processes and devices that allow to evaluate the thermal conductivity of materials used in construction. The problem with these devices is that they do not allow the evaluation of real-scale construction walls, with which important information is lost that allows to determine with greater precision the thermal behavior of the wall.

There are commercial solutions that allow to determine the thermal characteristics in construction materials, such as the EP-500 device of the German company Lambda Messtechnik, which measures the resistance to thermal transfer in accordance with ISO 8302. The difference is that it is limited the maximum size of the sample at 50 x 50 cm, which makes it impossible to test the behavior of a wall on a real scale.

Kosny and Christian (Kosny, J., Christian, J., 2001. Whole wall thermal performance, Oak Ridge National Laboratory, accessed at: http: bweb.ornl.gov/scl/roofs+walls/research/detailed_papers/Whole_Wall_Therm/, on February 28, 2014) proposed a method to measure thermal efficiency in building systems. The difference of the device developed in this investigation is that a sealed hot box (or hot box) is used; which increases costs and adds complexity to the process.

OBJECT OF THE INVENTION The invention consists of an apparatus for measuring thermal properties of real-scale construction systems, walls of 1.20 base by 2.10 m high. The device allows to measure samples of various materials of prefabricated type or masonry, with one or several layers of different materials that form a constructive system.

DESCRIPTION OF THE INVENTION The present invention deals with a device with which we obtain thermal values of a construction system, which allow us to calculate the thermal conductivity value of a composite system. For this it is necessary to have a sample which is introduced into the system by means of support vehicles. Once inside the system closes with a piston arrangement which allows us to isolate the sample from the environment. It is provided with heat and cold by means of a power source and chiller respectively and the measurement is measured by means of thermocouples supported with retractable devices that guarantee contact with the sample. Once the temperatures are stabilized and standardized, the measurement has been completed and the data is removed. The run is finished when the devices are turned off and the machine is stopped and turned off with the Off button. It is not necessary to remove the sample from the system if measurements are required later.

PROCESS DESCRIPTION The device treats of a machine with which thermal values of a constructive system are obtained, which allow to calculate the value of thermal conductivity of a compound system.

First the specimen is built on a wooden base filled with thermal insulation that is on the main sample holder (fig.10) that has metal bearings to slide the sample into the device, which in turn is on the sample holder external (Figure 11) that serves as support to keep the sample upright, it has the necessary supports to prevent it from tilting, also has free direction bearings to manipulate the sample outside the device.

Once the sample is made and it is dried in the case of samples that use mixtures with water, it is introduced inside the device. For this, the external sample holder (Fig. 11) is aligned with the internal sample holder (Fig. 9). Once the sample carriers are aligned, the main transport (Fig. 11) is transferred to the interim of the device on the internal transport (Fig. 9).

The system is closed, first the fiberglass is placed on the sides of the sample as a support insulator, then the side doors are closed and the system is sealed completely, for this all service and maintenance doors must be to be closed.

The power button of the machine that is in control part (18) is activated and all the systems will be energized. The support equipment that is the source of power (13), the computer equipment (14 and 15), the data acquisition (15) and the chillers (17) are turned on. Once all the equipment is turned on, the Start button is activated and by means of a control system (18) which contains a PLC which in turn controls an electro valve which will be the passage of air to activate the pistons that close the valve. internal sample holder (Fig. 9), hot plate (11) and top cover (Fig. 8) in that order, respectively, the latter attached to a specially manufactured base for this task (7).

Once the system is closed, the LoggerNet computer program is instructed to start making the measurements temperature. Heat is provided to the system by means of a power source (13) to which voltage and amperage values for the power supply are given. The opposite case, who will take care of the heat removal will be the chillers (17) fed by water with the capacity to cool it to the freezing point, they are activated and they are given the desired fluid temperature, this in turn circulates through the coolers (Fig. 14) to achieve heat removal.

Since the system is measuring and the temperatures are being provided to the wall, the system will be monitored by the aforementioned software to whom a data acquisition system to which seventy-two type K thermocouples are connected will provide information.

The thermocouple has a retractable device (Figure 15) that serves as a support to ensure contact with the wall, because if this amount with a deviation, is pando or how much rugosity it would not be possible to ensure contact with a static system. The operation of the device is very basic, it is a damping system supported by an internal spring, similar to a pneumatic piston has its stem and is bordered by the center, hole that allows us to slide the thermocouple inside, same as It is stuck with a high resistance additive to the tip of the shank making sure that it will not come out of its place. These devices (Fig. 15) are positioned crosswise on both cold (12) and hot (11) plates.

In the upper part of the system there are three indicator lights of the process (Fig. 19) which will tell us if the machine is on, running a measurement or in emergency stop.

The measurement ends when, through the software, we can observe stability and uniformity in the system.

The obtained data is downloaded to an Excel file.

To stop the system all the support devices are turned off and the Stop button in the control box (18) is pressed, at that moment the insulation panels of the machine will be opened and the Off button will be pressed.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows an isometric view of the device and its component parts.

Figure 2 shows the main structure of the device on which the clamping of the other parts depends.

Figure 3 shows the base that serves as support for the moving carriage of the hot plate and the pistons that move it.

Figure 4 shows the carriage that is the moving part of the hot plate, which is responsible for the closure between the plates.

Figure 5 shows the frame of the hot plate containing the resistors and the aluminum plate.

Figure 6 shows the frame of the cold plate containing the coolers.

Figure 7 shows the support of the pistons of the seal cap and upper insulation.

Figure 8 shows the upper seal cover and insulation.

Figure 9 is a view of the internal sample holder of the device.

Figure 10 is a view of the main sample holder in which the sample is directly constructed.

Figure 11 is a view of the external sample holder and support of the main sample holder.

Figure 12 shows the furniture that serves as the basis for the complementary equipment.

Figure 13 shows the rails of the internal sample holder with guides to correct trajectories.

Figure 14 shows the type of cooler used to remove heat from the system.

Figure 15 shows the retractable device for thermocouple that guarantees contact with the surface of the sample.

Claims (3)

CLAIMS Having sufficiently described my invention, I consider it a novelty and therefore claim as my exclusive property contained in the following claims:

1. An apparatus for measuring the thermal properties of construction systems, characterized in that it comprises: to. The means to perform tests of thermal properties in real scale construction systems, placing the sample between a hot plate and a cold plate, b. The means for inducing heat on one side of the sample by means of a hotplate device by means of electrical resistances, controlled by feedback to an automatic control system, c. The means to induce cold on the other side of the sample by means of a cold plate device, controlled by a cooling or chiller system. d. The means to measure the temperature between the hot plate and the sample, by means of an array of sensors connected to the means to digitize the signal and process it in a computer, e. The means to measure the temperature between the cold plate and the sample, by means of an array of sensors connected to the means to digitize the signal and process it in a computer, F. The means to isolate the space where the test will be made of the environmental conditions external to the test, within the device, g. The means to fix the sample by means of pneumatic pistons, controlled by a programmable logic controller.

2. The apparatus for measuring the thermal properties of construction systems, characterized by having an automated control system that allows testing without human intervention.

3. An arrangement of temperature sensors, characterized in that it contains the means for ensuring contact between said sensors and the sample by means of a retractable system, which presses the temperature sensor with the sample by means of a spring, and the means for fixing those sensors to a system that contains them in a matrix.