The use of air conditioning compressors in the room is intended to be used in the production work efficiency inspection
Compressor model compressors have a wide variety of structures, and modeling by mechanism is difficult. According to the performance curve provided by the manufacturer, this paper uses the graphical method <1, 2> to model the flow and power consumption to characterize the compressor performance.
The modeling idea is based on the analysis of the performance curve. Firstly, the performance curve when the condensation temperature tcond=40 is fitted, and based on this, the performance relationship under other tcond is fitted, and finally the actual superheat is corrected. The specific expression of the model is as follows: mass flow: mr = mr1 (tevap) - mr2 (tevap) (tcond-40) power: P = P1 (tevap) + P2 (tevap) (tcond-40) where: mr1 (tevap ) The mass flow equation of the compressor at tcond=40, the expression is: mr1(tevap)=tcond=40, the power fitting equation of the compressor, the expression is: P1(tevap)=-18182tevap+10418P2(tevap)tcond For each additional power change caused by 1 increase, the expression is: P2(tevap)=047727tevap+1477322 Condenser and evaporator model divide the condenser and evaporator into three and two phase zones according to the refrigerant flow state. Each different phase region is divided into several micro-elements, and the flow characteristics are analyzed for any one of the micro-member segments. The basic model equations are established based on the three laws of conservation and further discretized. The iterative algorithm adopts the dichotomy method, which has better simplicity and robustness. Finally, the refrigerant outlet state is determined by the actual length of the heat exchanger. The single microelement equation is as follows: mass conservation U=Gr momentum conservation (ie pressure calculation equation)-P2-P1x=12mdiGr2m+Gr2-1x energy conservation AiUhrx=di
i(Tw-Tr) micro-element outside the air side heat transfer equation mahrx = 0d0 (Tw-Tr) (Note: the above is the condenser equation, if it is an evaporator, the right side of the equation must be multiplied by the coefficient of moisture evolution) above the difference equation There are many parameters involved. These parameters are the preconditions for closing and solving the equations. The empirical formulas of each parameter are as follows: the selection coefficient of the relevant parameters in the heat exchanger model. The condenser evaporator refrigerant single-phase zone Dittus-Boeler Formula <6>
Friction coefficient Arit Suri formula <7>=011di+68Rer025 Refrigerant and air thermal property parameters convert the thermal property parameters into a database, and look up the table in the program to obtain the 23 capillary model, assuming that the refrigerant inside the tube is a one-dimensional adiabatic flow, Divided into two regions, supercooled and saturated, and consider critical flow. The adiabatic capillary has no heat exchange, the dynamic response time constant is very small, and the steady state equation modeling has sufficient accuracy. Based on the three conservation equations of continuous fluid medium, a capillary distribution parameter simulation model is established. The simulation results are in good agreement with the experimental data in the literature <3>, indicating that the model has good accuracy. The model equation is as follows: mass equation 1u1=2u=Gr energy equation h1+12Gr212=h2+12Gr2=hst momentum equation-(P2-P1)x=Gr2(2-1)x+mmGr22di24 system model component model is only the refrigeration system simulation Foundation, in order to finally complete the simulation of the system, we should also fully consider the mutual coupling relationship between the components, seek the refrigeration cycle balance point, and propose a stable discriminant function. According to the module structure of the actual object, the flow sequence of the refrigerant and certain constraints <4>, the component models are organically connected by appropriate node parameters (usually the exit parameter of the previous component is the import parameter of the latter component). , constitutes a simulation model of the entire cycle closed system.
The evaporation and condensing pressure determine the operating conditions of the refrigeration system as two iterative variables for the system simulation calculation. To ensure algorithmic rigor, there must be two iteration criteria. The most notable feature of the system state equilibrium point is that the refrigerant flow rates of the components are equal, which is used as the first iteration criterion. Reasonable superheat is beneficial to protect the normal operation of the compressor, which is the second iteration criterion. The iterative algorithm still uses the dichotomy method to give a calculation flow chart of the system steady-state simulation model.
Room air conditioner performance prediction results and analysis Room air conditioner main performance indicators are cooling capacity, compressor power consumption, COP, condensation and evaporation temperature. In the case of certain structural parameters, performance indicators are greatly affected by environmental conditions. In the past, most of the analysis of these impact results was obtained through experiments, which undoubtedly increased the work intensity and test time. Through the system simulation model, any working conditions encountered in actual operation can be realized, and the system performance indicators can be predicted and analyzed, which provides a valuable reference for product performance evaluation, component matching and clarification of some fuzzy concepts encountered in practice.
In this paper, an example air conditioner is used for simulation calculation. The structural parameters are as follows: (1) Condenser: Material: copper tube and aluminum fin rib spacing: 22mm tube spacing: 22mm model: 1005mm rib thickness: 02mm number of branches : 2 (2) Evaporator: Material: copper tube plus aluminum fin rib spacing: 22mm tube spacing: 20mm model: 1005mm rib thickness: 02mm number of branches: 2 (3) capillary: tube diameter: 15mm length: 1000mm (4) compressor: according to the fitting formula of part 21 (5) Refrigerant: R22 performance prediction of room air conditioner is to analyze the evaporator and condenser side air inlet under the condition that the structural parameters of each component of the system have been determined. The influence of parameters (temperature, flow) on system performance indicators, the input parameters include four variables. For the convenience of observation and analysis, the performance surface maps of each index parameter are given in two cases.
The inlet air parameters of the condenser side are unchanged, assuming that the inlet air parameters of the condenser side are unchanged, and the performance parameters of the analysis system vary with the air parameters of the evaporator side. The refrigeration system simulation model is used to calculate, and the cooling capacity Qe, the compressor power P, the COP, the condensation temperature Tc, the evaporation temperature Te, and the system circulating refrigerant flow rate mr are obtained, and the results are respectively shown as 7.
The inlet air parameters on the evaporator side are unchanged, assuming that the inlet air parameters on the evaporator side are unchanged, and the performance parameters of the analysis system vary with the air parameters on the condenser side. The system steady-state model is also used for simulation prediction. The performance surface is shown in 3.
According to the analysis, there are two opposite distributions of the trend of the second set of performance surface maps. The basic shape of both the cooling capacity and the COP are the same, and the performance surface is increasing with the decrease of the inlet air temperature Tairrin or the increase of the air volume mair. The change trend of the other four indicators is just the change of cooling capacity with the air parameters of the condenser inlet. The change of the air with the air parameters of the condenser. 0COP changes with the air parameters of the condenser inlet. 1 The condensing temperature changes with the air parameters of the condenser inlet. 2 The evaporation temperature is opposite to the change of the air parameters of the condenser inlet. They gradually decrease with the decrease of the inlet air temperature Tairrin or the increase of the air volume mair.
The previous method was used to analyze the influence of the air parameters on the condenser side on various performance indicators. At different inlet air temperatures, the air volume increased from 12135m3/h to 1699m3/h, with an increase of 40%. The average increase of cooling capacity and COP is: the refrigerant flow rate changes with the air parameter of the condenser inlet; the compressor power The average decreases corresponding to the condensing temperature, evaporation temperature and refrigerant flow rate are: 44%, 54%, 62% and 04%, respectively. Under different air volumes, the condenser inlet air temperature decreased from 40 to 30, only 25%, but the average increase in cooling capacity and COP increased significantly, respectively: 92% and 23%; compressor power, condensing temperature The average decrease in evaporation temperature and refrigerant flow significantly increased: 112%, 138%, 146%, and 08%, respectively.
As with the first set of performance surfaces, the air inlet temperature affects the performance index more than the air volume. In other words, the performance index is more sensitive to the inlet air temperature than to the air volume. It can be seen from the size of the lifting frame that the COP is most affected by the air parameters on the condenser side, followed by the evaporation temperature, followed by the condensation temperature, the compressor power, the cooling capacity, and finally the refrigerant flow rate, which is extremely small.
Conclusion Through the room air conditioner simulation model to simulate the actual operation of the refrigeration system, the performance index of the air conditioner product under full working condition can be predicted, and the quantitative analysis of the variation of the inlet air volume and the inlet air temperature of each index with the heat exchanger side can be made. The following conclusions can be drawn: (1) When the air parameters on the condenser side remain unchanged, the performance parameters increase with the increase of the inlet air temperature or air volume of the evaporator. The evaporation temperature is most affected by the air parameters on the evaporator side, and the compressor power is the smallest. (2) When the air parameters on the evaporator side remain unchanged, as the inlet air temperature of the condenser decreases and the air volume increases, the cooling capacity and COP show an upward trend, while the remaining performance indicators show a downward trend. The COP is most affected by the air parameters on the condenser side and the refrigerant flow rate is the smallest.
1. An open structure of heating elements with half round stainless steel
reflectors for an optimal use of energy.
2. The Gyros will change direction automatice, if there is a force.
3. Removable and detachable parts for easy clean.
4. The particular broiling result is obtained by alternating heating and
cooling down. The meat fibres do not harden, and the gravy is flavoured
by the spices. This cooking mode results in very healthy meat.
5. The vertical grill allows broiling meat layers, shashlik, party sausages,
poultry and fish with few attachments.
6. The Skewers and Gyros go in opposite direction so that the food could
be heated more well.
7. Power: 1400W
Vertical Electric Grill,Electric Vertical Grill,Vertical Bbq Grills,Indoor Vertical Grill
Housoen Electric Manufacture Co., Ltd. , https://www.housoenappliances.com