JPS5864490A - Operation of heating system using metal hydride - Google Patents

Abstract

PURPOSE:To extend the time of using the titled system at a stabilized temperature by elongating a constant characteristic operaion zone by a method wherein the heat source for a transitional characteristic operation zone at the initial stage of hydrogen adsorbing and heat radiating operation of the titled system is made up for by the calorific power of another heat source so as to bring about a constant heat radiating condition as early as possible and thence the hydrogen adsorbing reactions of the metal hydride are utilized. CONSTITUTION:In the transitional characteristic operation zone at the initial stage of the hydrogen adsorbing and heat radiating operation by the titled heating system, the required heat is supplied from an external heat source 2 and an auxiliary heat source 13 until a target heat radiating temperature T1 is reached so that a constant operation temperature is obtained quickly after the initiation of the operation of the heating system. As a consequence, the system can be operated at the target temperature T1 for a prolonged period of time thereby improve the thermal efficiency of the system.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of operating a heat utilization system using metal hydrides.

It is known that hydrogen storage metals such as TiFe and CaNi become metal hydrides through activation (hydrogenation), absorb and desorb large amounts of hydrogen, and generate heat during the occlusion process and endotherm during the devolatilization process. By utilizing this property of metal hydrides, natural energy such as solar heat and wind power, as well as factory waste heat, can be stored in the form of chemical energy called hydrogen.
It is possible to create a heat utilization system that can extract stable heat as needed.

An example of a conventional heat utilization system based on this principle will be explained with reference to FIG. , a heat exchange means 10 provided in the heat exchange section 6 and connected to the external heat source 2 and supplying the heat to the metal 5;
and a heat exchange means 11 which is connected to the heat radiating section 4 in the heat utilization device 3 and recovers the heat generated when the metal 5 absorbs hydrogen.

In order to accumulate and recover heat such as solar heat using this system, the heat from the external heat source 2 is transferred to the metal 5 in the metal holding container 1 under certain temperature and pressure conditions through the heat exchange means 10.
The metal 5 devolatilizes hydrogen, and the devolatilized phosphorous gas is stored in the hydrogen gas tank 7 via the pipe 8! When this hydrogen desorption operation is completed, the stop valve 12 provided in the hydrogen gas pipe 8 is closed.

During hydrogen storage heat dissipation operation, when the stop valve 12 is opened,
The hydrogen gas stored in the hydrogen gas tank 7 is transferred to the pipe 8 due to the pressure difference.
The metal 5 absorbs hydrogen and generates heat. The heat is recovered by the heat medium fluid flowing inside the heat exchange means 11, and is radiated to the heat utilization device 3 from the heat radiating section 4 in the heat utilization device 3.

Now, the heat generated during the above-mentioned hydrogen storage operation is initially used to heat the metal 5 itself and the holding container 1, so the heat dissipation characteristics of the metal 5 are as shown in FIG. From the starting point 0 to the time τ fake, the heat dissipation temperature gradually increases,
After 1 hour, the heat radiation source level reaches the target value peak and the heat is steadily radiated, and the characteristic curve has a transient characteristic region from 0 to time and a period from τ〇- until hydrogen absorption reaches saturation. A steady characteristic region of .

From the perspective of heat utilization, it is necessary to keep the transient characteristics as short as possible and to obtain heat as stable as possible for as long as possible. For this reason, various ideas have been made in the past. For example, metal holding containers were required to have a structure with low heat capacity and low heat transfer coefficient, but since this container functions as a heat exchanger and a pressure vessel, However, there were limits to the reduction of heat capacity and thermal conductivity.

The present invention eliminates the above-mentioned drawbacks of the conventional hydrogen storage and heat dissipation operation method for heat utilization systems using metal hydrides, and lengthens the steady-state characteristic range to extend the limited calorific value of metals at as stable a temperature as possible. The purpose is to provide a driving method that allows time to be utilized.

This objective is achieved according to the present invention by supplementing the transient characteristic region until a steady heat radiation state is reached with only the amount of heat generated due to hydrogen storage at the initial stage of hydrogen storage and heat radiation operation, with the amount of heat from other heat sources.

Hereinafter, the present invention will be explained in detail with reference to the drawings showing embodiments.

FIG. 3 shows an embodiment of an apparatus in which the conventional heat utilization system shown in FIG. 1 is improved to be suitable for carrying out the operating method of the present invention. This apparatus is the same as the conventional apparatus shown in FIG. 1 except that the following means are added. The metal hydride holding container 1 includes an auxiliary heat source 13 such as fuel or electric power in addition to heat exchange means 10 and 11 connected to an external heat source 2 such as solar heat or wind power and a heat radiating section 4 in the heat utilization device 3. heat exchange means 1 connected to
4 are provided.

The hydrogen storage and heat dissipation operation of the heat utilization system configured as described above is performed as follows.

As explained in Figure 2, at the beginning of hydrogen storage and heat release operation, a considerable portion of the heat generated due to hydrogen storage is spent heating the metal hydride itself and its holding container, resulting in a transient region in heat release characteristics. It is.

, Now, in the operating method of the present invention, during this transition period (between O and C shown in Figure 2), the amount of heat insufficient to radiate heat at the target heat radiation temperature T is compensated for by supplying it from another heat source. Do it like this.

The heat supply from the external heat source 2 and the auxiliary heat source 13 continues until the target heat radiation temperature T1 is reached, and as a result, the heat radiation temperature characteristics rapidly reach the steady state temperature after the start of operation, as shown by the chain line in Figure 2. The system can be operated stably for a long time at the target temperature T, which has a significant effect on improving the thermal efficiency of the system.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a conventionally devised heat utilization system using a metal hydride, FIG. Figure 3 is a diagram showing an example of a system for carrying out the method of the present invention.

Claims (1)

[Claims] In the operating method of a system in which a metal hydride is held in a container, hydrogen is absorbed into the metal, and the heat generated at that time is radiated to a heat utilization device. An operating method characterized by quickly obtaining a steady heat radiation state by supplementing the amount of heat from a heat source, and then stably extracting heat by utilizing an absorption reaction of metal hydride.