CN100557535C - A control method of a retractable roof heat shielding device - Google Patents

Abstract

The invention discloses a control method of a retractable roof heat-shielding device. By using the control method, according to the indoor thermal environment requirements and the radiant heat flow direction between the roof and the relative indoor enclosure structure, the heat shielding device arranged in parallel under the roof can be controlled. The expansion and retraction of the heat shielding device are automatically controlled to achieve the purpose of improving the indoor thermal environment. The control method of the roof heat shielding device proposed by the present invention has remarkable heat insulation effect, can effectively reduce the radiant heat entering and exiting the room through the roof layer; and by controlling the expansion and retraction of the heat shielding device, the indoor thermal environment can be improved to the greatest extent , to improve indoor thermal comfort, suitable for slope roofs (with or without suspended ceilings), flat roofs (with or without suspended ceilings), double-layer ventilated roofs and other roof forms.

Description

A control method of a retractable roof heat shielding device

technical field

The invention relates to a heat insulation control method, in particular to a control method of a retractable roof heat shielding device.

Background technique

Improving the heat insulation performance of the roof is especially important to reduce the solar radiation heat entering the building through the roof in summer, and it is an important measure to improve the indoor thermal environment. At present, the commonly used roof thermal insulation technology is to lay a thermal insulation layer on the structural layer of the roof, and then lay a roof with a waterproof layer and a protective layer. Thermal performance does not guarantee a good thermal environment indoors.

Using highly reflective materials to improve the summer heat insulation capacity of the roof is a new technical measure, which is usually used in double-layer ventilated roofs. A layer of highly reflective materials is attached to the lower surface of the upper roof to reduce the heat transfer through the roof in summer. However, due to the fixed material layer, when the indoor temperature is low in winter and the outdoor solar radiation is strong, the solar radiant heat is blocked from entering the room, and this heat cannot be effectively used to increase the indoor temperature.

Contents of the invention

In view of the above-mentioned defects in the prior art, the present invention provides a control method for a retractable roof heat shielding device, which can be installed under the roof according to the indoor thermal environment requirements and the direction of radiation heat flow between the roof and the relative indoor enclosure structure The deployment and retraction of the heat shielding device are automatically controlled to control the radiant heat entering and exiting the room through the roof, so as to improve the indoor thermal environment.

In order to achieve the purpose of the above invention, the technical solution adopted by the present invention is: a control method of a retractable roof heat shielding device, which detects the temperature of the lower surface of the roof and the surface of the relative enclosure structure under the roof in real time, and compares the temperature The difference judges the heat flow direction between the roof and the relative enclosure structure under the roof; then compares the detected indoor temperature with the preset reference value to judge the indoor thermal environment, and combines the above two factors to control the expansion of the heat shielding device or put away.

The present invention achieves the purpose of improving the indoor thermal environment by controlling the heat-shielding device arranged between the roof of the building and the indoor enclosure structure under the roof. The heat-shielding device is arranged between the roof and the relative indoor enclosure structure under the roof. It can also be folded up. When unfolded, it is parallel to the upper surface of the roof and at a certain distance. The heat shielding device is made of low-emissivity and high-reflectivity materials with a small thickness, forming a heat shielding layer under the roof. For buildings, when the summer climate is hot and the solar radiation is strong, the solar radiation heat entering the room through the roof of the building seriously affects the indoor thermal environment. According to the weakening principle of radiation heat transfer, heat shielding devices are arranged under the roof in summer. It can effectively reduce the radiant heat entering the room and improve the indoor thermal environment; in winter, when the outdoor solar radiation is strong and the room temperature is low, the solar radiant heat entering the room through the roof is a favorable factor for improving the indoor thermal environment. If the heat-shielding device is still arranged under the roof, the solar radiation heat entering the room through the roof will be weakened; except for the typical situation when the solar radiation is strong in winter and summer, at night, transitional seasons, rainy weather and other climate conditions, the roof If there is a temperature difference with the indoor enclosure structure under the roof, there will still be radiant heat entering and leaving the room through the roof, which will have a favorable or unfavorable impact on the indoor thermal environment.

Through the control method of the retractable roof heat shielding device of the present invention, the indoor thermal environment of the building can be effectively improved, the energy consumption of indoor air conditioning or heating can be reduced, and it is an efficient and self-adaptive roof heat insulation control method . This method is applicable to roof forms such as sloping roofs (with or without suspended ceilings), flat roofs (with or without suspended ceilings), and double-layer ventilated roofs.

Description of drawings

Figure 1 is a schematic diagram of the heat shield;

Fig. 2 is the structural diagram of the control system realizing the control method of the present invention;

Fig. 3 is a control schematic diagram of the present invention;

Fig. 4 is the control flowchart described in the embodiment;

In the attached picture:

1-upper surface 2-lower surface 3-heat shield

201-Surface temperature sensor under the roof 202-Surface temperature sensor of the relative enclosure structure under the roof

203-Indoor temperature sensor 204-Controller

205-Heat shielding device

Detailed ways

Referring to Figure 1, the weakening effect of the heat-shielding device on the radiation heat exchange between the roof and the relative indoor enclosure structure under the roof is realized through the following principles:

According to the basic principle of radiation heat transfer in heat transfer: in order to reduce the radiation heat transfer between the two surfaces, the method of arranging a heat shield between the two radiation surfaces can be adopted. The so-called heat shield refers to a thin plate arranged between two radiative heat transfer surfaces to weaken the radiative heat transfer.

The following is an example of placing a heat shield with low emissivity between parallel plates to reduce the radiation heat transfer between two parallel plates to illustrate the working principle of the heat shield, assuming that the emissivity of the two plates ε ₁ =ε ₂ =0.8, and the emissivity of the heat shield ε ₃ =0.2, then:

q ₁₃ ＝ε ₁₃ (E _b1 -E _b3 ) (1)

q ₃₂ =ε ₃₂ (E _b3 -E _b2 ) (2)

In the formula, q _{1, 3} and q _{3, 2} are the radiation heat exchange heat flux density of the upper surface 1 to the heat shield 3 and the heat shield 3 to the lower surface 2, respectively. The system emissivity of the surface 1, 3 and surface 3, 2 systems are respectively:

${\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 13</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 0.8</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 0.2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.1905</span>}$

${\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 32</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 0.2</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 0.8</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.1905</span>}$

The emissivity of the two systems is equal, so ε ₁₃ =ε ₃₂ =ε _s =0.1905.

Under thermal steady-state conditions, q ₁₃ =q ₃₂ =q ₁₂ , adding formulas (1) and (2) gives:

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="q"\; filenames="C20081003133600091.png,C20081003133600101.png"\; state="\{\{state\}\}"><figure-callout\; id="2"\; label="q"\; filenames="C20081003133600091.png"\; state="\{\{state\}\}">q</figure-callout></figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1,2</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.09525</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$

When no heat shield is arranged, the heat flux density of the radiation heat exchange between the upper surface 1 and the lower surface 2 is:

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="q"\; filenames="C20081003133600091.png,C20081003133600101.png"\; state="\{\{state\}\}"><figure-callout\; id="2"\; label="q"\; filenames="C20081003133600091.png"\; state="\{\{state\}\}">q</figure-callout></figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1,2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$

$<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$

$<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 0.8</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 0.8</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$

$<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; 6667</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$

Comparing the heat flux density of radiation heat transfer with and without the heat shield, it shows that the radiation heat transfer between surface 1 and surface 2 after the heat shield is arranged is 1/7 of that without the heat shield, and the radiation heat transfer is greatly reduced. In order to make the effect of weakening the radiation heat transfer more significant, the heat shield can actually be made of materials with lower emissivity. If a heat shield with an emissivity of 0.05 is arranged between two parallel surfaces with an emissivity of 0.8, the radiation heat can be reduced to 1/27 of the original.

Referring to Fig. 2, the temperature sensor 201 on the lower surface of the roof is arranged on the lower surface of the uppermost roof, and the temperature sensor 202 on the surface of the lower surface of the roof relative to the enclosure structure is arranged in different positions for different roof forms: for flat roofs or sloping roofs without a suspended roof layer , it is arranged on the indoor ground surface under the roof; for a flat or sloping roof with a suspended ceiling, it is arranged on the upper surface of the suspended ceiling; for a double-layer ventilated roof, it is arranged on the upper surface of the lower roof; the indoor air temperature sensor 203 is placed indoors. The heat shielding device 205 is arranged in parallel at a certain distance below the uppermost roof, and the controller 204 controls the unfolding and retracting of the heat shielding device 205 according to the signals of the temperature sensors 201 , 202 and 203 .

Referring to Figure 3, first set two different indoor high temperature reference values TH and low temperature reference values TL, and then use the temperature sensor to continuously measure the temperature of three measuring points: indoor air temperature T0, roof lower surface temperature T1, roof lower surface temperature Relative to the surface temperature T2 of the enclosure structure, and convert it into an electrical signal and transmit it to the controller 204 . Compare the indoor air temperature T0 with two indoor high temperature reference values TH and low temperature reference values TL to judge whether the indoor temperature is too high, too low or moderate, and then compare the roof lower surface temperature T1 with the relative enclosure structure surface temperature under the roof T2 is compared to determine the direction of the radiation heat transfer between the two surfaces at this time. When the temperature T1 of the lower surface of the roof is higher than the surface temperature T2 of the relative enclosure structure under the roof (T1>T2), it means that the radiation heat transfer is from the roof Pass to the room, and vice versa. When the direction of radiation heat transfer is from the roof to the room, if the indoor temperature is high at this time, the controller 204 acts to keep the heat shielding device 205 in the unfolded state, and if the indoor temperature is low at this time, the controller 204 acts to maintain the shielding The heat device 205 is in the retracted state; when the direction of radiation heat transfer is from the indoor to the roof, and the indoor temperature is high at this time, the heat shield device is kept in the retracted state through the action of the controller 204, and the indoor temperature is low at this time, Then the controller 204 acts to keep the heat shielding device 205 in the unfolded state; if the indoor temperature is moderate at this time, then keep the heat shielding device to maintain the current state unchanged.

Fig. 4 is a flow chart of the control method of the heat shielding device of the present invention.

After the heat shielding device, temperature sensor and controller are arranged, the indoor air high temperature reference value TH and low temperature reference value TL are set by the controller 204, and the high temperature reference value TH>low temperature reference value TL. (Step S1, TH>TL, TH and TL are set to 27°C and 20°C, respectively). The temperature sensors 201, 202, 203 continuously measure the temperature T1 of the lower surface of the roof, the surface temperature T2 of the relative enclosure structure under the roof, and the indoor air temperature T0 (step S2), and send them to the controller 204. In the controller 204, the indoor air temperature T0 is compared with the high temperature reference value TH and the low temperature reference value TL (step S3):

1) When the measured indoor air temperature T0 is greater than the high temperature reference value TH, it means that the indoor air temperature is too high and needs to be cooled. In the controller 204, the temperature T1 of the lower surface of the roof is compared with the surface temperature T2 of the relative enclosure structure under the roof ( Step S4), then perform the following operations according to the comparison result of T1 and T2:

① When T1 is higher than T2 by more than M°C (M is set to be 1°C), the controller 204 acts to make the heat shielding device 205 reach the unfolded state (step S6).

② When T1 is lower than T2 by more than M°C (M is set to 1°C), the controller 204 operates to make the heat shielding device 205 reach the retracted state (step S8).

③ When T2-M≤T1≤T2+M (M is set to 1°C), the controller 204 does not operate, and the heat shielding device 205 maintains the current state (S7).

2) When the measured indoor air temperature T0 is lower than the low temperature reference value TL, it means that the indoor air temperature is low and needs to be heated up. In the controller 204, the temperature T1 of the lower surface of the roof is compared with the surface temperature T2 of the relative enclosure structure under the roof ( Step S5), then perform the following operations according to the comparison result of T1 and T2:

① When T1 is higher than T2 by more than M°C (M is set to be 1°C), the controller 204 acts to make the heat shielding device 205 reach the retracted state. (step S8)

② When T1 is lower than T2 by more than M°C (M is set to be 1°C), the controller 204 acts to make the heat shielding device 205 reach the unfolded state (step S6).

③ When T2-M≤T1≤T2+M (M is set to 1°C), the controller 204 does not operate, and the heat shielding device 205 maintains the current state (S7).

3) When the measured indoor air temperature T0 is between the high temperature reference value TH and the low temperature TL, that is, TL≤T0≤TH, it means that the indoor air temperature is moderate, and the controller 204 does not operate, so that the heat shielding device 205 maintains the current state ( S7).

Through the corresponding actions of the controller 204, after the heat shielding device 205 completes the operation of step 6, 7 or 8, it enters step 2 again, and then continuously measures the temperatures T0, T1 and T2.

Claims (3)

1. A control method for a retractable roof heat shielding device, characterized in that the temperature of the lower surface of the roof and the surface of the relative enclosure structure under the roof is detected in real time, and the temperature difference between the roof and the lower surface of the roof is determined by comparing the temperature difference. The direction of heat flow between the enclosure structures; then compare the detected indoor temperature with the preset reference value to judge the indoor thermal environment, and combine the above two factors to control the expansion or retraction of the heat shielding device; combine the heat flow Controlling the shielding device based on orientation and thermal environmental conditions includes the following steps: 1) When the measured indoor air temperature T0 is greater than the indoor high temperature reference value TH, then compare the surface temperature T1 under the roof with the surface temperature T2 of the relative enclosure structure under the roof: ①When T1 is higher than T2 by more than M℃, control the expansion of the heat shielding device; ②When T1 is lower than T2 by more than M℃, control the heat shielding device to put away; ③When T2-M≤T1≤T2+M, the heat shielding device is kept in the current state through the controller; Where M is the operating limit set to avoid frequent operation; 2) When the measured indoor air temperature T0 is lower than the low temperature reference value TL, then compare the surface temperature T1 under the roof with the surface temperature T2 of the relative enclosure structure under the roof: ①When T1 is higher than T2 by more than M℃, control the heat shielding device to put away; ②When T1 is lower than T2 by more than M℃, control the expansion of the heat shielding device; ③When T2-M≤T1≤T2+M, control the heat shielding device to maintain the current state; 3) When the measured indoor air temperature T0 is between the high temperature reference value TH and the low temperature reference value TL, that is, TL≤T0≤TH, the heat shielding device is controlled to maintain the current state. 2. The control method of the retractable roof heat-shielding device according to claim 1, wherein the high temperature reference value TH of the indoor air temperature is set to 27°C, and the low temperature reference value TL is set to 20°C. 3. The control method of the retractable roof heat-shielding device according to claim 1, wherein the M is 1°C.

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