CN108278918A - Organic medium-temperature phase-change heat storage material - Google Patents

Abstract

The present invention discloses the use of an organic compound as a phase change heat storage material. The melting temperature of the compound during heat storage is 134-136°C, and the solidification temperature during heat release is 111-134°C; the phase change heat storage density is 130-136 J/g, and when the organic phase change material absorbs and stores heat energy, the heat source temperature should be controlled within the range of 136-160°C. The organic phase change material can store heat energy obtained from solar energy, industrial waste heat, or heating using off-peak electricity from the power grid, and the stored heat energy can be used for indoor heating of buildings or for driving absorption refrigeration to solve the problem of mismatch between heat energy supply and use in space or time, and improve energy utilization efficiency.

Description

An organic medium temperature phase change heat storage material

technical field

The invention relates to the use of an organic compound as a phase-change heat storage material, specifically, using an organic compound to absorb or release a large amount of heat energy through phase transition, so as to solve the problem of mismatch between heat energy supply and use in space or time, and improve Energy efficiency.

Background technique

The current high price of fossil energy and increasingly serious environmental problems make people pay more and more attention to the development and utilization of clean energy and the efficient use of energy. Among them, solar energy is an outstanding representative of clean energy, while industrial waste (waste) heat recovery and power grid peak-shaving and valley-filling are effective means to improve energy utilization efficiency.

The development and utilization of solar energy through light-to-heat conversion, that is, solar thermal utilization, has the advantages of high conversion efficiency and no pollution. However, there are fluctuations in solar radiation, and there are usually temporal or spatial differences between heat production by solar thermal utilization and the use of thermal energy, so the problem of thermal energy storage must be solved. Heat energy is the energy form that people use most. In people's production and life, many activities or processes need to use heat energy. Industrial waste heat has the characteristics of high temperature, high heat energy grade and large heat energy generation. Therefore, realizing the recovery and utilization of industrial waste heat is an important means to realize the efficient utilization of heat energy. However, there is usually a mismatch in time or space between the generation of industrial waste heat and the utilization of heat energy. Therefore, the problem of heat energy storage must also be solved. In addition, when the power system is running, there are always periodic fluctuations at the user end. Converting the electric energy provided by the power grid during the valley period into heat energy and storing it for use during the peak period of power consumption can not only generate huge economic benefits, but also contribute to the stability of the power grid. run. Therefore, thermal energy storage is an important means to develop new energy sources and improve energy utilization efficiency. Phase change heat storage materials are the first choice to solve the problem of thermal energy storage.

Absorption refrigeration uses thermal energy to drive a refrigerator to work to obtain cold energy. The heat energy obtained through solar-to-heat conversion, industrial waste heat recovery, and power grid peak-shaving valleys can all be used to drive the absorption chiller, but the prerequisite is that the temperature of the heat source must be above 80°C, and within a certain range, the heat source The higher the temperature, the more efficiently the refrigerator works. To achieve this goal, it is first required that the temperature of the heat energy extracted from the phase change heat storage material be higher than this temperature, so the exothermic phase change temperature of the phase change heat storage material is required to be higher than 80 °C. Since this temperature is very close to the boiling point of water, and the heat source temperature required by the double-effect absorption refrigerator is even higher, the choice of phase change heat storage materials is very limited. For example, common hydrated salt phase-change materials will fail due to dehydration; there are very few types of organic phase-change materials with suitable phase-change temperatures. Therefore, it is very necessary to find new phase change heat storage materials with suitable phase change temperature and good heat storage capacity to meet the needs of new energy development and energy utilization efficiency improvement.

Contents of the invention

The object of the present invention is to provide an application of an organic compound as a phase change heat storage material in the field of thermal energy storage. The compound can store or release heat energy through phase change, solve the problem of mismatching heat energy supply and use in space or time, and improve energy utilization efficiency.

In order to achieve the above object, the present invention adopts the following technical solution: the use of an organic compound as a phase change heat storage material. The compound molecule has the following structure: ; The compound can store or release thermal energy through phase transition; the melting temperature of the compound is 134~139°C when storing heat, and the solidification temperature is 111~134°C when exothermic; the heat storage density of phase change is 130~136 J/ g, the relationship between the heat capacity and temperature of the compound in the solid state between -75 and 125°C is: , the relationship between heat capacity and temperature between 140 ~ 160 ℃ in liquid state is: , C _p ( s ) and C _p ( l ) in the above two formulas are the heat capacity of solid and liquid respectively, the unit is J/(℃·g), T is the temperature, the unit is ℃; this compound is used for phase transition When the heat storage material absorbs and stores heat energy, the temperature of the heat source should be in the range of 140~160°C.

The organic phase-change material can store heat energy obtained from solar energy, industrial waste heat, or electricity heating during off-peak periods of the power grid, and use the stored heat energy for indoor heating of buildings or to drive absorption refrigerators for cooling.

When the organic phase-change material stores heat energy obtained from solar energy, industrial waste heat, or heating by using electric energy in the off-peak period of the power grid, the phase-change material is placed in a certain container, and then the container containing the phase-change material is combined with the solar energy. Heat collectors, industrial waste heat sources or electric heaters are in direct contact to heat the phase change material to melt, or transfer heat energy from solar collectors, industrial waste heat sources or electric heaters to the container through heat transfer fluid phase change material and heating the phase change material to melt it, etc., the heat transfer medium can be water vapor or heat conduction oil.

When the thermal energy stored in the phase change material is used for indoor heating of a building or to drive an absorption refrigerator for cooling, it is necessary to use a heat transfer medium to transfer the heat energy from the phase change material to the indoor heater or the absorption refrigerator. The working medium can be water or heat transfer oil; when water is used as the heat transfer working medium, the hot water heated by the phase change material can also be directly used as domestic hot water.

When the thermal energy stored by the phase change material is used for heating in the building or driving an absorption refrigerator to cool through the heat transfer of the working medium, the temperature of the working medium heated by the phase change heat storage material can be reached before heating. Continuously adjustable within the range of 130°C.

The present invention has the following advantages.

The invention provides the application of using an organic compound as a phase-change heat storage material to store heat energy derived from solar energy, industrial waste heat and power grid valley period electric energy. The organic phase change heat storage material has suitable heat absorption and release temperature, high heat storage capacity and good long-term use stability. The heat energy stored by the organic phase change heat storage material can be used as a heat source for driving an absorption refrigerating machine or directly as an indoor living heat source.

Detailed ways

The present invention will be described in further detail below in conjunction with specific examples. In the following examples, various types of heat sources are used to directly heat the phase-change heat storage material with an electric heater to simulate providing thermal energy for the phase-change heat storage material, but these examples do not limit the scope of the invention.

Example 1.

Take about 5 mg of organic phase change material, and carry out differential scanning calorimetry on TA Q2000 differential scanning calorimeter at a heating rate of 10 °C/min from room temperature to 150 °C, and the melting point of the organic phase change material is measured as 137 ~ 139°C, the melting enthalpy is about 136 J/g; take about 5mg of organic phase change material, on the TA Q2000 differential scanning calorimeter, at a heating rate of 10°C/min, in the range of 50°C to 150°C After 50 cycles of differential scanning calorimetry, the melting point of the organic phase change material has been stable in the range of 134-139°C, the solidification temperature has been in the range of 111-134°C, and the melting enthalpy has been stable in the range of 130-136 J/g. within range.

Example 2.

Bending a copper tube with an outer diameter of 5mm and a wall thickness of 0.3mm into a coil tube with a tube spacing of 5mm and a disc diameter of 4.5 cm, a total of 4 layers of discs, and put the coil tube into a 1cm-thick asbestos material around it Add 100g of organic phase change material to the wrapped 150mL straight glass, bury the coil, cover the mouth of the cup with insulation material, lift the end of the coil 2cm out of the cover and connect it to the heat-resistant rubber hose; The temperature of the heater is 140°C. Heat the glass from the bottom to melt all the organic phase change materials. Stop heating and feed tap water at 25°C into the coil to control the flow of water. The outlet water temperature can be controlled to 60°C.

Example 3.

Control the temperature of the electric heater in Example 2 to 160°C, heat the glass from the bottom to completely melt the organic phase change material, stop heating, and pass heat conduction oil at 25°C into the coil to control the flow of the oil. Control the outlet oil temperature to 110°C.

Example 4.

Control the temperature of the electric heater in Example 2 to 160°C, heat the glass from the bottom to completely melt the organic phase change material, stop heating, and pass heat conduction oil at 25°C into the coil to control the flow of the oil. Make the outlet oil temperature gradually rise to 130°C and stabilize at this temperature.

Claims (5)

1. a kind of purposes of organic compound as phase-change heat-storage material, it is characterised in that the compound molecule has following knot Structure：；The compound can store by phase transformation or discharge thermal energy, and solve thermal energy makes for giving Used in space or temporal mismatch problem, the utilization ratio of the energy is improved；Fusion temperature when the compound heat accumulation is 134 ~ 139 DEG C, setting temperature when heat release is 111 ~ 134 DEG C；Phase-change thermal storage density be 130 ~ 136J/g, the compound in solid-state- The relationship between thermal capacitance and temperature between 75 ~ 125 DEG C is：, in liquid The relationship between thermal capacitance and temperature between 140 ~ 160 DEG C is：, in upper two formulaC _p (s) WithC _p (l) thermal capacitance when being respectively solid-state and liquid, unit is J/ (DEG C g), and T is temperature, and unit is DEG C；The compound is used as When phase-change heat-storage material absorbs and stores thermal energy, heat source temperature should control within the scope of 136 ~ 160 DEG C.

2. purposes of the organic compound according to claim 1 as phase-change material, it is characterised in that the organic phase-change material Material can store from waste heat more than solar energy, industry or heated using electric-net valley phase electric energy and the thermal energy that obtains, and by storage Thermal energy is for Indoor environment heat supply or driving absorption refrigeration mechanism cold.

3. purposes of the organic compound according to claim 2 as phase-change material, it is characterised in that the organic phase-change Material storage from solar energy, industry more than waste heat or using electric-net valley phase electric energy heat and obtain thermal energy when, be by phase transformation material Material is placed in a constant volume device, then will fill waste heat heat source or electrical heating more than the container of phase-change material and solar thermal collector, industry Device is in direct contact to be allowed to melt with heating phase-change material, or by heat-transfer working medium by thermal energy from solar thermal collector, industry more than give up The methods of heat source or electric heater pass to the phase-change material in container and heating phase-change material is allowed to melt to realize, described Heat-transfer working medium can be water vapour or conduction oil.

4. purposes of the organic compound according to claim 2 as phase-change material, it is characterised in that described by phase transformation material Material storage thermal energy for Indoor environment heat supply or driving absorption refrigeration mechanism cold when, need to use heat-transfer working medium by thermal energy from Phase-change material is conveyed to household heater or Absorption Refrigerator, and the working medium can be water or conduction oil；When using water conduct When heat-transfer working medium, the hot water heated by phase-change material can also be used directly as domestic hot-water.

5. the thermal energy according to claim 4 by phase-change material storage by refrigerant heat transfer for Indoor environment heat supply or When driving absorption refrigeration mechanism cold, it is characterised in that Temperature of Working after phase-change heat-storage material heats can working medium before heating Temperature is continuously adjusted in the range of 130 DEG C.