CN111678278B - Preheating type air source heat pump frost inhibition system and method - Google Patents
Preheating type air source heat pump frost inhibition system and method Download PDFInfo
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Abstract
The invention discloses a preheating type air source heat pump frost suppression system and a frost suppression method. Part of outdoor air is changed into preheated air after exchanging heat with indoor air in the sensible heat exchanger, enters a preheating mixing box to be mixed with the other part of outdoor air, and then enters an outdoor unit of an air source heat pump for exchanging heat; and the control system acquires indoor and outdoor environmental parameters according to the temperature and humidity sensor and adjusts the preheating air volume ratio of the sensible heat exchanger under different outdoor conditions. Compared with the outdoor air at the same moment, the temperature of the mixed air is increased, the relative humidity is reduced, and the frosting rate is reduced. Under different outdoor conditions, the frost inhibition system can obviously reduce or even prevent the frosting rate of the air on the surface of the air source heat pump outdoor unit; the frosting inhibiting effect is achieved under the frosting working condition of low temperature and high humidity, and meanwhile, the COP (coefficient of performance) reduction condition caused by low temperature of the air source heat pump unit can be improved.
Description
Technical Field
The invention belongs to the technical field of air source heat pumps, and particularly relates to a preheating type air source heat pump frost suppression system and a frost suppression method.
Background
Under the working condition of the air source heat pump in winter, when the temperature of outdoor air is low and the relative humidity is high, the surface temperature of an evaporator fin is lower than the dew point temperature of the air and lower than 0 ℃, the surface of an evaporator of an outdoor unit of the air source heat pump is frosted, and the problems of insufficient heat absorption of a refrigerant in the evaporator, low temperature of the refrigerant, low pressure of suction and exhaust of a compressor, low heating capacity and COP (coefficient of performance) of a unit and the like are caused. If defrosting is not performed in time, the comfort of indoor personnel is affected, and the operation of the whole system is damaged. At present, the air source heat pump system generally adopts a reverse circulation mode to defrost, although the defrosting can be rapidly realized by the mode, the phenomenon of blowing cold air even can occur when the indoor heat supply is stopped during defrosting, and the indoor thermal comfort is seriously influenced. In addition, when the unit is defrosted, the temperature and the pressure of a refrigerant in the system are changed violently, unit components are impacted, and the stability of the unit operation is damaged, so that higher requirements on the reliability of the unit components are provided by defrosting. In order to enable the unit to perform the defrosting operation accurately and quickly, an effective defrosting control strategy needs to be set. The control strategies related to air source heat pump defrosting mainly comprise: temperature-time defrosting control method, air pressure difference defrosting control method, indoor and outdoor double-sensor defrosting control method, etc., but these methods can not completely remove frost, so that the phenomenon of 'wrong defrosting' can not be avoided. The heating efficiency of the unit is further deteriorated by the wrong defrosting.
The existing research shows that when the outdoor air temperature is less than 6 ℃ and the relative humidity is more than 50%, the air source heat pump has the risk of frosting. If the outdoor air parameters are in the range for a long time, even if the unit can effectively defrost, the unit is always in a frosting-defrosting cycle, the root problem of frosting is not solved, the normal operation of the unit is very unfavorable, and the indoor thermal comfort is poor. Therefore, if the air state parameters of the inlet of the outdoor evaporator of the air source heat pump can be changed, the formation of frost can be delayed or even blocked, and the defrosting times of the unit are effectively reduced or even frost is not generated, so that the indoor thermal comfort is better ensured, and the long-time stable operation of the unit is ensured.
At present, researchers place an electric heating element at an inlet of an outdoor unit of an air source heat pump, and directly preheat outdoor air in an electric heating mode to achieve the aim of inhibiting frost. Although the frost inhibition effect can be obtained by the method, the electric energy is high-grade energy, and the method for directly heating the air by using electricity converts the high-grade energy into low-grade energy, which is obviously not energy-saving. Meanwhile, another researcher designs an auxiliary heating frost suppression system, a heat dissipation copper pipe and fins are arranged around the air source heat pump outdoor evaporator, a boiler is used for heating water and introducing the water into the heat dissipation copper pipe, and air at the inlet of the air source heat pump outdoor evaporator is preheated. The method can also obtain the effect of inhibiting frost, but the auxiliary heating frost inhibiting system adopts parts such as a boiler, a heat preservation water tank, a circulating water pump, a heating copper pipe and the like, so that the system is complex, and the applicability to small household air source heat pumps is not strong. Meanwhile, the boiler is used for heating water, heating copper pipes and fins by the water, and heating air by the copper pipes and the fins, wherein the heat exchange loss is increased due to the fact that multiple heat exchange processes are needed.
The air source heat pump is an efficient energy-saving device, and the energy efficiency ratio of the air source heat pump in winter operation can often reach more than 3. This approach is clearly more energy efficient than the above approach if the heat generated by the air source heat pump can be used to preheat the air at the inlet of the outdoor evaporator for frost suppression purposes. In this regard, some studies have been conducted by researchers: under the working condition in winter, a combined system of a heat recovery fresh air system and an air source heat pump system is researched, and the indoor exhaust air temperature after heat recovery is higher than that of outdoor air, so that the air is sent to an inlet of an air source heat pump evaporator and mixed with other air to realize the improvement of the air temperature entering an outdoor unit, and the aim of suppressing frost is further realized. However, under the working condition of winter, although the indoor air has higher temperature, the moisture content is higher than that of the outdoor air, so the method can cause the temperature of the mixed air to be increased and the moisture content to be increased at the same time, and the condition that the frosting rate is not reduced and is increased can occur, and the opposite effect is achieved. And the air volume of the indoor exhaust air is determined by the indoor fresh air volume which is fixed under the normal condition, so the frost inhibition effect under different outdoor conditions is uncontrollable.
Disclosure of Invention
In order to solve the defects in the prior art, the invention aims to provide a preheating type air source heat pump frost suppression system and a frost suppression method. Meanwhile, the optimization of the frost inhibition effect under different outdoor conditions can be ensured by adjusting the preheating air quantity.
The invention is realized by the following technical scheme.
A preheating type air source heat pump frost suppression system comprises a sensible heat exchanger, a preheating mixing box, an air pipe, an air source heat pump outdoor unit and an air source heat pump indoor unit, wherein the sensible heat exchanger is communicated with the preheating mixing box through the air pipe; the air source heat pump outdoor unit is communicated with the air source heat pump indoor unit through a refrigerant pipeline to form an air source heat pump unit;
indoor air enters the sensible heat exchanger from the indoor air inlet, and is sent back to the indoor from the indoor air outlet after heat exchange; outdoor air enters the sensible heat exchanger from the outdoor air inlet through the air pipe to be subjected to heat exchange to become preheated air, enters the preheating mixing box from the outdoor air outlet through the air pipe, is mixed with the other part of outdoor air entering from the inlet of the preheating mixing box, and then enters the outdoor unit of the air source heat pump to be subjected to heat exchange;
the control system acquires indoor and outdoor environmental parameters according to the temperature and humidity sensor, and performs preheating air volume ratio adjustment on the sensible heat exchanger, so that the outdoor air and the indoor air perform dividing wall type sensible heat exchange in the sensible heat exchanger, and the frost inhibition of the frost inhibition system is realized.
Further, the preheating air volume ratio is the ratio of the air volume of the sensible heat exchanger to the air volume of the air source heat pump outdoor unit.
Furthermore, a heat exchange core body and a small fan connected to a control system are arranged in the sensible heat exchanger, and the heat exchange core body is made of aluminum foil.
Furthermore, the heat-insulating layer is arranged outside the preheating mixing box, the air inlet of the outdoor unit of the air source heat pump is completely covered, and the outdoor air subjected to heat exchange in the sensible heat exchanger is mixed with the other part of outdoor air entering the preheating mixing box from the inlet of the preheating mixing box.
Further, the air source heat pump unit is an air source heat pump hot air heater or an air source heat pump hot water heater.
The invention further provides a preheating type air source heat pump frost suppression method, which adjusts the preheating air volume ratio according to outdoor parameter conditions and comprises the following steps:
1) temperature and humidity sensor for monitoring indoor air temperature tnAnd relative humidity
Outdoor air temperature taAnd relative humidity
2) The control system judges whether the outdoor air parameters are in the frosting area according to the monitoring values of the temperature and humidity sensors: if ta<At 6 ℃ and
step 3) is entered, otherwise, the monitoring is continued, and the judgment of the step is repeated after the interval time T;
3) the control system starts the sensible heat exchanger to preheat and calculates the air temperature t after the mixing of the inlet of the air source heat pump outdoor unitxAnd relative humidity
4) Calculating the air frosting rate of the surface of the outdoor unit of the air source heat pump under the condition of the current outdoor parameters;
5) if the frost rate v of outdoor airiLess than or equal to 0.05mm/h, outputting the adjustable preheating air quantity ratio thetaiThe air quantity is a sensible heat exchanger air quantity regulating value;
if v isiIf > 0.05mm/h, i ═ i +1, substitute θ'i＝i+1Repeating the steps 3) -5);
if theta is calculatedi＝6Frost formation rate v of outdoor air at 30%i＝6And v isi＝6If the thickness is more than 0.05mm/h, the output is thetai＝630% is the preheating air quantity ratio regulating value of the sensible heat exchanger;
6) after a time interval T, steps 1) -6) are repeated. The interval time T is 30-60 min.
Due to the adoption of the technical scheme, the invention has the following beneficial effects:
the invention preheats the outdoor air by utilizing the heat generated by the air source heat pump, thereby improving the temperature of the air entering the outdoor machine of the air source heat pump, reducing the relative humidity, reducing the surface frosting rate of the evaporator of the outdoor machine and further realizing the frosting inhibition effect. Meanwhile, compared with other methods for heating outdoor air temperature by electric heating or other modes to achieve the same frost inhibition purpose, the method provided by the invention utilizes the heat generated by the air source heat pump, and the heating efficiency of the air source heat pump is higher than that of the electric heating or other heating modes, so that the frost inhibition effect is achieved and the method is more energy-saving than the method. In addition, under certain frosting working conditions of low temperature and high humidity, outdoor air is preheated through the system, the frosting inhibiting effect is achieved, meanwhile, the COP (coefficient of performance) reduction caused by low temperature of the air source heat pump unit can be improved, and the heating efficiency of the unit is improved. Therefore, under the working conditions, compared with a conventional air source heat pump without preheating, the system has the advantages that the same indoor heat supply effect is guaranteed, meanwhile, the electric power is lower, and the system has better energy-saving performance.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention:
fig. 1 is a schematic diagram of a preheating type air source heat pump frost suppression system of the invention.
FIG. 2 is a flow chart of a method for calculating and adjusting the preheating air volume ratio under different outdoor parameters.
In fig. 1: 1. a sensible heat exchanger; 2. preheating a mixing box; 3. an air duct; 4. an indoor air inlet; 5. an indoor air outlet; 6. an outdoor air inlet; 7. an outdoor air outlet; 8. preheating an inlet of a mixing box; 9. an air source heat pump outdoor unit; 10. an air source heat pump indoor unit; 11. a refrigerant conduit; 12. temperature and humidity sensor.
Detailed Description
The present invention will now be described in detail with reference to the drawings and specific embodiments, wherein the exemplary embodiments and descriptions of the present invention are provided to explain the present invention without limiting the invention thereto.
Referring to fig. 1, the preheating type air source heat pump frost suppression system provided in the embodiment of the present invention includes a sensible heat exchanger 1, a preheating mixing tank 2, an air duct 3, an air source heat pump outdoor unit 9, an air source heat pump indoor unit 10, a refrigerant duct 11, and a temperature and humidity sensor. The air source heat pump outdoor unit 9 is communicated with the air source heat pump indoor unit 10 through a refrigerant pipeline 11 to form an air source heat pump unit; the air source heat pump unit is an air source heat pump air heater or an air source heat pump water heater.
The sensible heat exchanger 1 is connected with four air ports through air pipes, indoor air enters the sensible heat exchanger 1 from an indoor air inlet 4, and is sent back to the indoor from an indoor air outlet 5 after heat exchange; outdoor air enters the sensible heat exchanger 1 from an outdoor air inlet 6, becomes preheated air after heat exchange, is discharged into the preheating mixing box 2 from an outdoor air outlet 7, is mixed with another part of outdoor air entering from an inlet 8 of the preheating mixing box in the preheating mixing box, and then enters an outdoor unit 9 of an air source heat pump for heat exchange. Compared with the outdoor air at the same moment, the mixed air has the same moisture content, the temperature is increased, the relative humidity is reduced, and the frosting rate is reduced.
The air volume of the sensible heat exchanger 1 can be automatically adjusted according to outdoor parameter conditions and the type of the air source heat pump, so that the frost inhibition effect of the frost inhibition system is ensured. The control system acquires indoor and outdoor environmental parameters according to the temperature and humidity sensor 12, and performs preheating air volume ratio adjustment on the sensible heat exchanger 1, so that the outdoor air and the indoor air perform dividing-wall type sensible heat exchange in the sensible heat exchanger 1, and the frost inhibition of the frost inhibition system is realized.
In order to make the result more universal, the air volume value of the sensible heat exchanger is converted into relative volume, and the ratio of the air volume of the sensible heat exchanger to the air intake volume of the air source heat pump outdoor unit is called as preheating air volume ratio.
Wherein, the sensible heat exchanger 1 is provided with a heat exchange core body and a small fan connected to a control system, and the heat exchange core body is made of aluminum foil. It is placed indoors and is connected with four air ports through air pipes. The air quantity of the small fan is adjustable, and the air quantity of the small fan is adjusted according to the difference of the outdoor air temperature and the outdoor air humidity, so that the system can obtain the maximum frost inhibition effect. Indoor air and outdoor air are subjected to recuperative sensible heat exchange in the heat exchange core.
The temperature exchange efficiency eta of the sensible heat exchanger is 70-80%, namely the heat exchange efficiency value which can be reached by the current commercial sensible heat exchanger product. The reason for using sensible heat exchange rather than full heat exchange with higher heat exchange efficiency is: in winter, outdoor air has a relatively low moisture content due to a relatively low temperature even though the relative humidity of the air is high; the indoor air has higher temperature and lower relative humidity, but the moisture content of the air is usually larger than that of the outdoor air, so the latent heat exchange direction under the action of the moisture content difference is the indoor-to-outdoor wind transfer. Therefore, the total heat exchanger is selected to not only raise the temperature of the outdoor air but also raise the moisture content. Compared with the results of using the total heat exchanger and the sensible heat exchanger, if the temperature exchange efficiency of the total heat exchanger and the sensible heat exchanger is equal, the relative humidity of outdoor air is smaller after heat exchange is carried out by using the sensible heat exchanger, so that the frosting rate is reduced more favorably, and the frosting inhibiting effect is achieved.
The air pipe can adopt a circular air pipe with smaller resistance, the arrangement of the air pipe can be adjusted according to the indoor position of the sensible heat exchanger, and the air pipes of the indoor air inlet and the indoor air outlet can be omitted and directly enter and exit air from two air ports of the sensible heat exchanger.
The heat-insulating layer is arranged outside the preheating mixing box 2, so that heat loss can be effectively reduced. The preheating mixing box 2 covers all air inlets of the air source heat pump outdoor unit 9, and a better heat exchange effect is guaranteed. The outdoor air after heat exchange in the sensible heat exchanger 1 is mixed with another part of outdoor air entering the sensible heat exchanger from the preheating mixing box inlet 8, and then enters the air source heat pump outdoor unit for heat exchange.
The mixed air has the same moisture content compared with the outdoor air at the same moment, the temperature is increased, and the relative humidity is reduced. When the air source heat pump is in the frosting working condition, the frosting inhibition system can effectively reduce the frosting rate of the air on the surface of the air source heat pump outdoor unit 10, so that the frosting inhibition effect is realized. In addition, under certain frosting working conditions of low temperature and high humidity, outdoor air is preheated through the system, the frosting inhibiting effect is achieved, meanwhile, the COP (coefficient of performance) reduction caused by low temperature of the air source heat pump unit can be improved, and the heating efficiency of the unit is improved. Therefore, under the working conditions, compared with a conventional air source heat pump without preheating, the system has the advantages that the same indoor heat supply effect is guaranteed, meanwhile, the electric power is lower, and the system has better energy-saving performance.
When the air source heat pump is operated in winter and outdoor parameters meet frosting conditions, the surface of the air source heat pump outdoor unit 9 is frosted, and the frosting inhibition system is started at the moment. The control system starts the sensible heat exchanger 1, the two fans of the sensible heat exchanger 1 are started, and the indoor air and the outdoor air are sucked from the air inlets of the indoor air inlet 4 and the outdoor air inlet 6 under the action of the fans and enter the heat exchange core body through the air pipe 3 to exchange heat. The preheated indoor air is sent back to the indoor from the indoor air outlet 5, and the arrangement position of the air port can be considered to be arranged at a wall corner where people do not move frequently because the temperature is lower than the indoor temperature, so that the influence on the indoor people is small. The heat-exchanged outdoor air is discharged into the preheating mixing box 2 from an outdoor air outlet 7. Two air flows are mixed in the preheating mixing box and then enter an air source heat pump outdoor unit for heat exchange. Compared with the outdoor air at the same moment, the temperature of the mixed air is increased, the relative humidity is reduced, the frosting rate is reduced, and the frosting inhibiting effect is realized. When the outdoor air state parameters change along with time, the frosting rate of the outdoor air on the surface of the air source heat pump evaporator also changes, so that the preheating air quantity is adjusted to ensure the frosting inhibition effect of the system.
It should be noted that, certain deviation exists in the frosting maps of the air source heat pump units of different models; in addition, different types of air source heat pump units may adopt different defrosting control strategies, such as a timing control method, a time-temperature method, an air pressure difference control defrosting method, a frost layer sensor control defrosting method and the like. These factors can cause the preheating type air source heat pump frost suppression system to generate different frost suppression effects under the same preheating air quantity.
Taking an air source heat pump and a sensible heat exchanger of a certain type as an example, the flow of the method for adjusting the preheating air volume ratio under different outdoor parameter conditions is shown in fig. 2, and the method mainly comprises the following steps:
1) temperature and humidity sensor for monitoring indoor air temperature tnAnd relative humidity
Outdoor air temperature taAnd relative humidity
2) The control system judges whether the outdoor air parameters are in the frosting area according to the monitoring values of the temperature and humidity sensors: if ta<At 6 ℃ and
step 3) is entered, otherwise, the monitoring is continued, and the judgment of the step is repeated after the interval time T;
3) the control system starts the sensible heat exchanger for preheating, and calculates the air temperature t after mixing at the inlet of the air source heat pump outdoor unit according to the following formulas (1) and (2)xAnd relative humidity
Wherein, txThe air temperature of the mixed air at the inlet of the air source heat pump outdoor unit is obtained;
mixing the air with the air source heat pump outdoor machine inlet to obtain the air relative humidity; thetaiFor adjustable preheating air quantity ratio, there are 6 gears respectively of thetai＝1＝5％、θi＝2＝10％、θi＝3＝15％、θi＝4＝20％、θi＝5＝25％、θi＝630%, substituting θ in initial calculationi＝1＝5％；ρrIs the preheated air density; h isrIs the enthalpy value of the preheated air; rhoaIs the outdoor air density; h isaIs the enthalpy value of outdoor air; omegaaIs the outdoor air moisture content; omegabxIs txSaturated humid air moisture content at temperature.
Moisture content of outdoor airQuantity omegaaIs calculated as follows:
wherein the content of the first and second substances,
relative humidity of outdoor air, omegabaIs taSaturated humid air moisture content at temperature;
temperature t of preheated airrAnd moisture content omegarIs calculated as follows:
ωr＝ωa；tr＝η·(tn-ta)+ta
wherein, ω isaIs the outdoor air moisture content; t is tnIs the temperature of the indoor air, taIs the outdoor air temperature; eta is the temperature exchange efficiency of the sensible heat exchanger, and is 70 percent;
density p of preheated airrIs calculated as follows:
wherein, trIs the preheated air temperature; omegarIs the preheated air moisture content;
outdoor air density ρaIs calculated as follows:
wherein, taIs the outdoor air temperature; omegaaIs the outdoor air moisture content;
enthalpy value h of preheated airrIs calculated as follows:
hr＝1.01tr+ωr·(2500+1.84tr)
outdoor air enthalpy value haIs calculated as follows:
ha＝1.01ta+ωa·(2500+1.84ta)。
4) calculating the frosting rate of the air source heat pump outdoor unit under the condition of the current outdoor parameters according to the following formula (3):
wherein v isiThe preheating air quantity ratio is theta under the condition of the current outdoor parametersiThe rate of frost formation of outdoor air; fitting coefficient k1～k5Respectively as follows: -1.59811, -0.05699, 0.00154, 0.03546, 0.00141. The frosting rate v is calculated during the initial calculation1。
5) If the frost rate v of outdoor airiLess than or equal to 0.05mm/h, outputting the adjustable preheating air quantity ratio thetaiThe air quantity is a sensible heat exchanger air quantity regulating value;
if v isiIf > 0.05mm/h, i ═ i +1, substitute θ'i＝i+1Repeating the steps 3) -5);
if theta is calculatedi＝6Frost formation rate v of outdoor air at 30%i＝6And v isi＝6If the thickness is more than 0.05mm/h, the output is thetai＝630% is the preheating air quantity ratio regulating value of the sensible heat exchanger;
6) repeating steps 1) to 6) after 30 minutes.
When the outdoor air state parameters are the cases described in the following a) to e), the actual frost suppressing effect using the frost suppressing system of the present invention is as follows. It should be noted that, the following 5 cases are only the frost inhibition effect achieved by the system under the condition of 5 specific outdoor parameters, and cannot include the frost inhibition effect of the system under all frosted outdoor parameters; the following comparative data of frosting rate and electric power are based on two air source heat pumps of the same type, one of which uses the frost suppressing system of the present invention and the other does not.
a) When the outdoor air temperature is 2 ℃, the relative humidity is 85%, the outdoor air is in a frosted heavy frost region. The preheating air volume ratio is set to be 30%, so that the surface frosting rate of the evaporator of the air source heat pump outdoor unit 9 can be reduced by 44.6%.
b) When the outdoor air temperature is-3 ℃ and the relative humidity is 85%, the outdoor air is in a general frosting area. The preheating air volume ratio is set to be 30%, so that the surface frosting rate of the evaporator of the air source heat pump outdoor unit 9 can be reduced by 49.0%.
c) When the outdoor air temperature is-8 ℃, and the relative humidity is 85%, the outdoor air is in a general frosting area. The preheating air volume ratio is set to 30%, so that the surface frosting rate of the evaporator of the air source heat pump outdoor unit 9 can be reduced by 71.3%. Meanwhile, because the outdoor air temperature is lower, the influence of low temperature on the unit heating performance is greatly relieved through preheating, so that the COP of the unit is greatly improved, the electric power of the air source heat pump unit is reduced by 4.9 percent compared with that of a conventional air source heat pump without preheating, and the energy saving performance of the whole system is better.
d) When the outdoor air temperature is-13 ℃ and the relative humidity is 85%, the outdoor air is in a general frosting area. The preheating air volume ratio is set to be 30%, the surface frosting rate of an evaporator of the air source heat pump outdoor unit 9 can be reduced by 97.6%, the frostless operation is basically realized, meanwhile, the electric power of the air source heat pump unit is reduced by 12.4%, and the energy saving performance of the whole system is very good.
e) When the outdoor air temperature is-18 ℃ and the relative humidity is 85%, the outdoor air is in the light frost region. The preheating air volume ratio is set to be 25%, so that the air source heat pump unit can realize frostless operation.
The present invention is not limited to the above-mentioned embodiments, and based on the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and modifications to some technical features without creative efforts according to the disclosed technical contents, and these substitutions and modifications are all within the protection scope of the present invention.
Claims (9)
1. A preheating type air source heat pump frost inhibition method is characterized in that,
the preheating type air source heat pump frost suppression system comprises a sensible heat exchanger (1), a preheating mixing box (2), an air pipe (3), an air source heat pump outdoor unit (9) and an air source heat pump indoor unit (10), wherein the sensible heat exchanger (1) is communicated with the preheating mixing box (2) through the air pipe (3); the air source heat pump outdoor unit (9) is communicated with the air source heat pump indoor unit (10) through a refrigerant pipeline (11) to form an air source heat pump unit;
indoor air enters the sensible heat exchanger (1) from the indoor air inlet (4), and is sent back to the indoor from the indoor air outlet (5) after heat exchange; outdoor air enters the sensible heat exchanger (1) from the outdoor air inlet (6) through the air pipe (3) to be subjected to heat exchange to become preheated air, enters the preheating mixing box (2) from the outdoor air outlet (7) through the air pipe (3), is mixed with the other part of outdoor air entering from the preheating mixing box inlet (8), and then enters the air source heat pump outdoor unit (9) to be subjected to heat exchange;
the control system acquires indoor and outdoor environmental parameters according to the temperature and humidity sensor (12), and performs preheating air volume ratio adjustment on the sensible heat exchanger (1), so that the outdoor air and the indoor air perform dividing-wall type sensible heat exchange in the sensible heat exchanger (1) to realize the frost inhibition of the frost inhibition system;
the preheating air volume ratio is the ratio of the air volume of the sensible heat exchanger to the air intake of the air source heat pump outdoor unit;
the method for adjusting the preheating air volume ratio according to outdoor parameter conditions comprises the following steps:
1) temperature and humidity sensor for monitoring indoor air temperature tnAnd relative humidity
Outdoor air temperature taAnd relative humidity
2) The control system judges whether the outdoor air parameters are in the frosting area according to the monitoring values of the temperature and humidity sensors: if ta<At 6 ℃ and
step 3) is entered, otherwise, the monitoring is continued, and the step is repeated after the interval time TJudging;
3) the control system starts the sensible heat exchanger for preheating, and calculates the air temperature t after mixing at the inlet of the air source heat pump outdoor unit according to the following formulas (1) and (2)xAnd relative humidity
Wherein, txThe air temperature of the mixed air at the inlet of the air source heat pump outdoor unit is obtained;
mixing the air with the air source heat pump outdoor machine inlet to obtain the air relative humidity; thetaiFor adjustable preheating air quantity ratio, rhorIs the preheated air density; h isrIs the enthalpy value of the preheated air; rhoaIs the outdoor air density; h isaIs the enthalpy value of outdoor air; omegaaIs the outdoor air moisture content; omegabxIs txSaturated humid air moisture content at temperature;
4) calculating the frosting rate of the air source heat pump outdoor unit under the condition of the current outdoor parameters according to the following formula (3):
wherein v isiThe preheating air quantity ratio is theta under the condition of the current outdoor parametersiTime and outdoor air frosting rate, k1～k5The coefficients obtained for the fitting;
5) if the frost rate v of outdoor airiLess than or equal to 0.05mm/h, the output is adjustable at the momentThe preheating air quantity ratio theta of the jointiThe air quantity is a sensible heat exchanger air quantity regulating value;
if v isiIf > 0.05mm/h, i ═ i +1, substitute θ'i＝i+1Repeating the steps 3) -5);
if theta is calculatedi＝6Frost formation rate v of outdoor air at 30%i＝6And v isi＝6If the thickness is more than 0.05mm/h, the output is thetai＝630% is the preheating air quantity ratio regulating value of the sensible heat exchanger;
6) after an interval of time T, steps 1) -5) are repeated.
2. The preheating type air source heat pump frost suppressing method according to claim 1, wherein in the step 3), the outdoor air moisture content ω isaThe calculation is as follows:
wherein the content of the first and second substances,
relative humidity of outdoor air, omegabaIs taSaturated humid air moisture content at temperature;
moisture content omega from outdoor airaObtaining the moisture content omega of the preheated airrFrom the outdoor air temperature taAnd the temperature t of the indoor airnCalculating to obtain the temperature t of the preheated airrThe following were used:
ωr＝ωa；tr＝η·(tn-ta)+ta
where η is the temperature exchange efficiency of the sensible heat exchanger.
3. The defrosting method of a preheated air source heat pump according to claim 1, wherein in the step 3), the preheated air density p isrThe calculation is as follows:
wherein, trIs the preheated air temperature; omegarIs the preheated air moisture content;
the outdoor air density ρaThe calculation is as follows:
4. the defrosting method of a preheated air source heat pump according to claim 1, wherein in the step 3), the enthalpy value h of the preheated air isrThe calculation is as follows:
hr＝1.01tr+ωr·(2500+1.84tr)
wherein, trIs the preheated air temperature; omegarIs the preheated air moisture content;
the enthalpy value h of the outdoor airaThe calculation is as follows:
ha＝1.01ta+ωa·(2500+1.84ta)。
5. the method as claimed in claim 1, wherein in the step 6), the time interval T is 30-60 min.
6. A preheating type air source heat pump frost suppression system is characterized by comprising a sensible heat exchanger (1), a preheating mixing box (2), an air pipe (3), an air source heat pump outdoor unit (9) and an air source heat pump indoor unit (10), wherein the sensible heat exchanger (1) is communicated with the preheating mixing box (2) through the air pipe (3); the air source heat pump outdoor unit (9) is communicated with the air source heat pump indoor unit (10) through a refrigerant pipeline (11) to form an air source heat pump unit;
indoor air enters the sensible heat exchanger (1) from the indoor air inlet (4), and is sent back to the indoor from the indoor air outlet (5) after heat exchange; outdoor air enters the sensible heat exchanger (1) from the outdoor air inlet (6) through the air pipe (3) to be subjected to heat exchange to become preheated air, enters the preheating mixing box (2) from the outdoor air outlet (7) through the air pipe (3), is mixed with the other part of outdoor air entering from the preheating mixing box inlet (8), and then enters the air source heat pump outdoor unit (9) to be subjected to heat exchange;
the control system acquires indoor and outdoor environmental parameters according to the temperature and humidity sensor (12), and performs preheating air volume ratio adjustment on the sensible heat exchanger (1), so that the outdoor air and the indoor air perform dividing-wall type sensible heat exchange in the sensible heat exchanger (1) to realize the frost inhibition of the frost inhibition system;
the preheating air volume ratio is the ratio of the air volume of the sensible heat exchanger to the air intake of the air source heat pump outdoor unit;
and is used to perform the following method:
the method for adjusting the preheating air volume ratio according to outdoor parameter conditions comprises the following steps:
1) temperature and humidity sensor for monitoring indoor air temperature tnAnd relative humidity
Outdoor air temperature taAnd relative humidity
2) The control system judges whether the outdoor air parameters are in the frosting area according to the monitoring values of the temperature and humidity sensors: if ta<At 6 ℃ and
step 3) is entered, otherwise, the monitoring is continued, and the judgment of the step is repeated after the interval time T;
3) the control system starts the sensible heat exchanger for preheating, and calculates the air temperature t after mixing at the inlet of the air source heat pump outdoor unit according to the following formulas (1) and (2)xAnd relative humidity
Wherein, txThe air temperature of the mixed air at the inlet of the air source heat pump outdoor unit is obtained;
mixing the air with the air source heat pump outdoor machine inlet to obtain the air relative humidity; thetaiFor adjustable preheating air quantity ratio, rhorIs the preheated air density; h isrIs the enthalpy value of the preheated air; rhoaIs the outdoor air density; h isaIs the enthalpy value of outdoor air; omegaaIs the outdoor air moisture content; omegabxIs txSaturated humid air moisture content at temperature;
4) calculating the frosting rate of the air source heat pump outdoor unit under the condition of the current outdoor parameters according to the following formula (3):
wherein v isiThe preheating air quantity ratio is theta under the condition of the current outdoor parametersiTime and outdoor air frosting rate, k1～k5The coefficients obtained for the fitting;
5) if the frost rate v of outdoor airiLess than or equal to 0.05mm/h, outputting the adjustable preheating air quantity ratio thetaiThe air quantity is a sensible heat exchanger air quantity regulating value;
if v isiIf > 0.05mm/h, i ═ i +1, substitute θ'i＝i+1Repeating the steps 3) -5);
if theta is calculatedi＝6Frost formation rate v of outdoor air at 30%i＝6And v isi＝6If the thickness is more than 0.05mm/h, the output is thetai＝630% is the preheating air quantity ratio regulating value of the sensible heat exchanger;
6) after an interval of time T, steps 1) -5) are repeated.
7. The preheating type air source heat pump frost suppressing system according to claim 6, wherein the sensible heat exchanger (1) is provided with a heat exchange core and a small fan connected to a control system, and the heat exchange core is made of aluminum foil.
8. The preheating type air source heat pump frost suppression system according to claim 6, wherein the preheating mixing box (2) is externally provided with a heat insulation layer to cover the air inlet of the air source heat pump outdoor unit (9), and the outdoor air after heat exchange in the sensible heat exchanger (1) is mixed with another part of the outdoor air entering the preheating mixing box from the inlet (8) of the preheating mixing box.
9. The preheating type air source heat pump frost suppression system according to claim 6, wherein the air source heat pump unit is an air source heat pump hot air heater or an air source heat pump hot water heater.
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| CN114893971A (en) * | 2022-05-13 | 2022-08-12 | 广东欧科空调制冷有限公司 | Screw type drying system |
| CN116293948A (en) * | 2023-03-17 | 2023-06-23 | 烟台湖科空调设备有限公司 | Air source air inlet structure |
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| CN100578099C (en) * | 2008-03-21 | 2010-01-06 | 闫成文 | Heat pump type air conditioner outdoor machine |
| CN106288224A (en) * | 2016-08-29 | 2017-01-04 | 广东工业大学 | The antifrost heat recovery system of new wind outside a kind of preheating chamber |
| CN109945467A (en) * | 2019-03-26 | 2019-06-28 | 珠海格力电器股份有限公司 | Air conditioner and its control method |
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