[0050] Example: An independent fresh air system with heat pipe heat exchanger (see Figure 2 to Figure 4 ), characterized in that it includes a pre-cooling unit 2, a cooling and dehumidifying unit 3, a reheating unit 4, and an air supply unit 5; the pre-cooling unit 2, the cooling and dehumidifying unit 3, the reheating unit 4 and the air supply unit 5 are installed in sequence Between the inlet and the outlet of the fresh air system; the air supply unit 5 is installed at the outlet of the fresh air system.
[0051] A filter unit 1 is installed at the entrance of the fresh air system. (see Figure 2 to Figure 4 )
[0052] A damper actuator M and an air pressure difference switch ΔP are installed at the inlet and outlet of the fresh air system; temperature and humidity sensors are installed on the inlet and outlet sides of the pre-cooling unit 2 and the reheating unit 4 TH; The air supply unit 5 is connected to the inverter V; the fresh air system is connected to the controller 13; the analog input terminal AI of the controller 13 is connected to the temperature and humidity sensor TH; the digital input terminal DI of the controller 13 Connect the air pressure difference switch ΔP; the analog output terminal AO of the controller 13 is connected to the inverter V and the electronic expansion valve 9 of the cooling and dehumidifying unit 3; the digital output terminal DO of the controller 13 is connected to the air valve actuator M. (see Figure 5 )
[0053] The pre-cooling unit 2 is the evaporator side 7 of the heat pipe heat exchanger 6, and the reheating unit 4 is the condenser side 12 of the heat pipe heat exchanger 6; the heat pipe heat exchanger 6 of the independent fresh air system is in the pre-cooling unit 2 And the reheating unit 4 realizes heat recovery. (see Figure 2 to Figure 4 )
[0054] The cooling and dehumidifying unit 3 is composed of a direct evaporator 8, an electronic expansion valve 9, a condenser 10 and a compressor 11; the output end of the direct evaporator 8 is connected to the input end of the compressor 11, The output end is connected to the input end of the condenser 10, the output end of the condenser 10 is connected to the input end of the electronic expansion valve 9, and the output end of the electronic expansion valve 9 is connected to the input end of the direct evaporator 8.
[0055] The filter unit 1 uses a filter.
[0056] The air supply unit 5 adopts a fan.
[0057] A working method of an independent fresh air system containing a heat pipe heat exchanger is characterized in that it includes the following steps:
[0058] (1) Outdoor fresh air OA is pre-treated by pre-cooling unit 2;
[0059] (2) The pre-treated outdoor fresh air OA is reprocessed by the cooling and dehumidifying unit 3;
[0060] (3) The fresh air is folded through the duct and then reheated by the reheating unit 4;
[0061] (4) The air supply unit 5 sends the treated air FA into the room, and controls the indoor temperature and humidity at 26°C±0.5°C, 50%±1% through the controller 13.
[0062] In the step (1), the fresh air is pre-cooled through the evaporator side 7 of the heat pipe heat exchanger 6; the processing process of the cooling and dehumidification unit 3 in the step (2): the refrigerant absorbs the external environment in the direct evaporator 8 The heat of the outdoor fresh air evaporates into gas and enters the compressor 11; the gas is compressed by the compressor 11 and the temperature rises; the gas discharged from the compressor 11 enters the condenser 10, is cooled by the cooling medium, and becomes a liquid; When the refrigerant liquid flows through the electronic expansion valve 9, the pressure and temperature are reduced, and it becomes a two-phase mixture composed of gas and liquid, and then enters the direct evaporator 8, and absorbs the heat from the objects surrounding the direct evaporator 8, which is the outdoor fresh air. The process of recooling the outdoor fresh air is completed; in the step (3), the fresh air is folded through the air pipe and then passes through the condenser side 12 of the heat pipe heat exchanger 6 for reheating.
[0063] In the step (4), the method for the controller 13 to control the indoor temperature and humidity at 26°C, 50% is: when the temperature and humidity of the indoor return air is higher than 26°C, 50%, the controller 13 adjusts the electronic expansion The opening of the valve 9 further increases the refrigeration capacity of the direct evaporator 8, and finally controls the indoor temperature and humidity at 26°C, 50%; when the indoor return air temperature and humidity are lower than 26°C, 50%, the same pass The controller 13 adjusts the opening of the electronic expansion valve 9, thereby reducing the refrigeration capacity of the direct evaporator 8, and finally controls the indoor temperature and humidity at 26°C, 50%; the controller 13 adjusts the opening of the electronic expansion valve 9 in real time In turn, the indoor temperature and humidity are controlled at 26℃±0.5℃, 50%±1%.
[0064] The technical effect comparison between the present invention and the prior art (see figure 1 ):
[0065] In order to compare and calculate the energy consumption advantages of the independent fresh air system proposed by the present invention and the traditional fresh air system, the following assumptions are made:
[0066] a. In these two systems, they are in the same state, from point a to point R. For example: the state point (point a) at the fresh air entrance, and the state point c and the interior design point (state point R).
[0067] b. The traditional fresh air system treats fresh air from state a to state c through refrigeration and dehumidification. However, if the heat pipe heat exchanger 6 is added, because it has a pre-cooling effect on the system, the dehumidification capacity of the system can be enhanced.
[0068] c. In the entire fresh air system, all flows are adiabatic processes.
[0069] d. The energy transfer of the evaporator side 7 and the condenser side 12 of the heat pipe heat exchanger 6 is equal, but in opposite directions. That is: when the air flow rate is constant, (h a -h b )=(h d -h c ).
[0070] e. In theory, the traditional system should include heating equipment to reheat the fresh air before sending fresh air to the room.
[0071] Energy saving calculation of fresh air system:
[0072] For systems without heat pipe heat exchanger 6, the cooling load and heat load of the fresh air system are as follows: Q DXN,O &H DX,O
[0073] Q DXN,O =ρV FA (h a -h c ) (1)
[0074] H DX,O =ρV FA C pa (t d -t c ) (2)
[0075] among them:
[0076] ρ=air density, kg/m 3
[0077] Cpa=specific heat of air, kJ/kg·K
[0078] V FA = Flow of fresh air, m 3 /s
[0079] h a = Enthalpy of outdoor air, kJ/kg
[0080] h c = The enthalpy value of the fresh air after being cooled, kJ/kg
[0081] t c = The temperature after the fresh air is cooled, ℃
[0082] t d = The temperature after fresh air reheats, ℃
[0083] In a system with heat pipe heat exchanger 6, when fresh air flows through the evaporator side 7 of heat pipe heat exchanger 6, the fresh air will be pre-cooled from t a Down to t b , But this process is constant humidity, h b Is the enthalpy value at point b after the fresh air is cooled by the evaporator side 7 of the heat pipe heat exchanger 6, and the cooling load of the direct evaporator 8 can be expressed as Q DX :
[0084] Q DX =ρV FA (h b -h c ) (3)
[0085] The fresh air passes through the direct evaporator 8 and will be reheated by the condenser side 12 of the heat pipe heat exchanger 6 to reach the state point d, and the temperature at this point is t d. The air state at points a to d is determined by the following formula:
[0086] t d =t c +η HP (t a -t c ) (4)
[0087] t b =t a -(t d -t c ) (5)
[0088] w a =w b (6)
[0089] w c =w d (7)
[0090] among them
[0091] t a = Outdoor temperature, ℃
[0092] t b = The temperature of the evaporator side 7 leaving the heat pipe heat exchanger 6, °C
[0093] η HP = Heat pipe efficiency
[0094] w s = Humidity of each air state point, kg/kg (s=a,b,c,d)
[0095] Therefore, after the state points a and c are determined, the air state points b and d can be calculated by formulas (4) to (7).
[0096] The cooling load of the entire fresh air system is as follows:
[0097] Q DX =ρV FA (h b -h c ) (8)
[0098] Reheat load:
[0099] H DX =0 (9)
[0100] Therefore, the reduction of the cooling load of the fresh air system can be calculated by formula (1) and formula (8):
[0101] △Q DX =Q DX,O -Q DX =ρV FA (h a -h c )-ρV FA (h b -h c )=ρV FA (h a -h b ) (10)
[0102] The reduction of the reheat load of the fresh air system can also be calculated by formula (2) and formula (9):
[0103] △H DX =H DX,O -H DX =H DX,O =ρV FA C pa (t d -t c ) (11)
[0104] Therefore, compared with the traditional system, the energy saving of the fresh air system proposed in this topic is as follows:
[0105] Δ Q DX Q DX , O = Q DX , O - Q DX Q DX , O = ρV FA ( h a - h c ) - ρV FA ( h b - h c ) ρV FA ( h a - h c ) = h a - h b h a - h c - - - ( 12 )
[0106] The energy savings of the fresh air system are as follows:
[0107] ϵ 1 = ΔQ DX COP + ΔH DX Q DX , O COP + H DX , O = Q DX , O + Q DX + COP ρV FA C pa ( t d - t c ) Q DX , O + COP ρV FA C pa ( t d - t c )
[0108] = ρV FA ( h a - h c ) - ρV FA ( h b - h c ) + COP ρV FA C pa ( t d - t c ) ρV FA ( h a - h c ) + COP ρV FA C pa ( t d - t c )
[0109] = h a - h b + COP C pa ( t d - t c ) h a - h c + COP C pa ( t d - t c ) - - - ( 13 )
[0110] among them
[0111] COP = coefficient of refrigeration
[0112] ε 1 = Energy saving of fresh air system,%
[0113] Energy saving calculation of air conditioning system
[0114] For systems without heat pipe heat exchanger 6, the cooling load and heat load of the fresh air system are as follows: Q DXN,O &H DX,O
[0115] Q DX,O =ρV FA (h a -h c ) (14)
[0116] Q FCN,O =ρV RA (h R -h c ) (15)
[0117] H DX,O =ρV S (h d -h c ) (16)
[0118] among them:
[0119] ρ=air density, kg/m 3
[0120] V RA = Air flow of return air, m 3 /s
[0121] V FA = Fresh air flow, m 3 /s
[0122] V S = Air supply volume, m 3 /s(V S =V RA +V FA )
[0123] h a = Enthalpy of outdoor air, kJ/kg
[0124] h c = The enthalpy value leaving the direct evaporator 8, kJ/kg
[0125] h d = The enthalpy of the air supply point, kJ/kg
[0126] h R = Indoor enthalpy value, kJ/kg
[0127] In a system with heat pipe heat exchanger 6, when fresh air flows through the evaporator side 7 of heat pipe heat exchanger 6, the fresh air will be pre-cooled from t a Down to t d , But this process is constant humidity, h b Is the enthalpy value at point b after the fresh air is cooled by the evaporator side 7 of the heat pipe heat exchanger 6, and the cooling load of the direct evaporator 8 can be expressed as Q DX :
[0128] Q DX =ρV FA (h b -h c ) (17)
[0129] The cooling load of the entire fresh air system is as follows:
[0130] Q DX =ρV FA (h b -h c ) (18)
[0131] Reheat load:
[0132] H DX =0 (19)
[0133] Therefore, the reduction in cooling load of the fresh air system can be calculated by formula (14) and formula (18):
[0134] △Q DX =Q DX,O -Q DX =ρV FA (h a -h c )-ρV FA (h b -h c )=ρV FA (h a -h b ) (20)
[0135] The reduction of the reheat load of the fresh air system can also be calculated by formula (16) and formula (19):
[0136] △H DX =H DX,O -H DX =H DX,O =ρV S (h d -h c ) (twenty one)
[0137] Energy saving of the entire air conditioning system:
[0138] ϵ 2 = Δ Q DX COP + ΔH DX Q DX , O COP + H DX , O + Q FCN , O COP = Q DX , O - Q DX + COP ρV S ( h d - h c ) Q DX , O + COP ρV S ( h d - h c ) + Q FCN , O
[0139] = ρV FA ( h a - h c ) - ρV FA ( h b - h c ) + COP ρV S ( h d - h c ) ρV FA ( h a - h c ) + COP ρV S ( h d - h c ) + ρV RA ( h R - h c )
[0140] = V FA ( h a - h b ) + COP V S ( h d - h c ) V FA ( h a - h c ) + COP V S ( h d - h c ) + V RA ( h R - h c ) - - - ( twenty two )
[0141] among them
[0142] ε 2 = Energy saving of air conditioning system,%
[0143] By comparing the two systems, the independent fresh air system containing the heat pipe heat exchanger 6 will inevitably produce energy-saving effects in the fresh air system. As long as the temperature is greater than or equal to 25 degrees Celsius and the relative humidity is greater than or equal to 50%, the independent fresh air system containing the heat pipe heat exchanger 6 can significantly reduce the cooling load and reheating load, and because the heat pipe heat exchanger 6 is used, the reheating equipment is also No need to use.
[0144] According to related assumptions, the cooling load energy saving can be converted into the final energy saving of the fresh air system and the air conditioning system, and the energy saving of the air conditioning system can be obtained between 6%-9%, and the energy saving of the intelligent building system is 3 %. The results show that an independent fresh air system containing heat pipe heat exchangers is suitable for civil and industrial intelligent buildings, and has considerable energy-saving potential.
