An active noise control method for a heat source tower heat pump system

Abstract

The present invention relates to an active noise control method for a heat source tower heat pump system, including: preliminarily setting the design selection of the heat source tower and the number of heat source tower groups; numerically simulating and calculating the flow field of each heat source tower under the rated air volume, as well as the noise superposition and propagation of the heat source tower groups, evaluating whether the noise value at the key monitoring points meets the daytime noise standard, and if not, adjusting the preliminary setting and re-performing the numerical simulation calculation; performing noise superposition and propagation simulation calculations for the finally set heat source tower groups under different air volumes, obtaining a curve graph of the relationship between the noise value and the air volume of the heat source tower, and determining the maximum air volume that meets the noise standard; performing heat and mass transfer simulation on each heat source tower, and under the maximum air volume limit, regulating the operating parameters of the heat source tower, and selecting a set of operating parameters corresponding to the minimum temperature difference between the inlet solution temperature and the inlet air temperature, that is, obtaining the optimal operating parameters for noise control. The present invention meets the control requirements of cost, heat transfer performance and ambient noise.

Description

Technical Field

[0001] The present invention relates to the technical field of heat source tower heat pumps, and in particular to an active noise control method for a heat source tower heat pump system. Background Art

[0002] The heat source tower heat pump system has become one of the preferred solutions for building air-conditioning cold and heat sources due to its dual high efficiency in refrigeration and heating. The main noise source of the heat source tower heat pump system in the environment during use is the heat source tower placed outdoors. Since the heat source tower is usually placed outdoors, its noise has an impact on the building and its surrounding environment. Therefore, whether it can meet the noise requirements of existing buildings and the surrounding environment has a crucial impact on the implementation of new construction or renovation projects of the heat source tower heat pump system.

[0003] At present, there are two ideas for effective heat source tower noise reduction methods: passive noise reduction and active noise reduction. The traditional passive noise reduction method is mainly achieved by setting sound absorption devices and sound insulation walls, etc. The cost of its noise reduction transformation is usually 2-4 times the cost of the heat source tower product, with a relatively high cost, and it often affects air flow and thus causes a decrease in the heat exchange performance of the heat source tower. In contrast, active noise reduction should be the preferred noise reduction method. Since the main noise of the heat source tower is the fan noise, active noise reduction is mainly achieved through the optimization of the heat source tower selection configuration and the control of the fan speed, etc. The problems existing in the current active noise reduction method are that the changes in air volume and heat exchange performance caused by the variable speed noise reduction of the fan do not match the requirements of the air-conditioning load. Therefore, it is urgent to design an active noise reduction method that can take into account the characteristics of air-conditioning load changes to meet the industrial application requirements. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides an active noise control method for a heat source tower heat pump system, aiming to meet the control requirements of cost, system heat exchange performance and surrounding environment noise.

[0005] The technical solution adopted by the present invention is as follows:

[0006] An active noise control method for a heat source tower heat pump system, comprising:

[0007] Preliminarily set the design selection of the heat source tower and the number of units of the heat source tower group according to the air-conditioning cold and heat design load;

[0008] Establish a heat source tower noise model, conduct numerical simulation calculations on the flow field of each heat source tower under the rated air volume, as well as the noise superposition and propagation of the heat source tower group, set key monitoring points, and evaluate whether the noise value at the key monitoring points meets the daytime noise standard, including: if not, adjust the heat source tower design selection and increase the number of heat source towers, and re-conduct numerical simulation calculations until the noise value corresponding to the set heat source tower design selection and number of units meets the daytime noise standard;

[0009] Perform noise superposition and propagation simulation calculations for the finally set heat source tower group under different air volumes, obtain the relationship curve between the noise values at key monitoring points and the air volume of the heat source tower, and determine the maximum air volumes of the heat source tower group that meet the daytime and nighttime noise standards respectively;

[0010] Establish a heat and mass transfer model of the heat source tower, obtain real-time air conditioning loads and weather parameters, conduct heat and mass transfer simulations on each heat source tower, and under the limitation of the maximum air volume, adjust the operating parameters of the heat source tower. During the adjustment process, select a set of operating parameters for which the temperature difference between the inlet solution temperature and the inlet air temperature of the heat source tower is the smallest, that is, obtain the optimal operating parameters for noise control.

[0011] The evaluation of whether the noise value at the key monitoring point meets the daytime noise standard further includes:

[0012] If it does not meet the standard, adjust the design and selection of the heat source tower and increase the number of heat source towers, and re-perform numerical simulation calculations. If the design and selection of the heat source tower and the number configuration have reached the optimal selection considering economic factors and still cannot meet the daytime noise standard, then adopt the method of increasing the solution flow rate of the heat source tower and reducing the air volume until the daytime noise standard is met.

[0013] The numerical simulation calculations for the flow field of each heat source tower and the noise superposition and propagation of the heat source tower group include:

[0014] Use CFD software to perform numerical simulation of the flow field of the heat source tower to obtain flow field information, obtain the aerodynamic noise spectrum information of the heat source tower through the FW-H model, and use noise prediction software to perform noise propagation simulation and superposition simulation on the heat source tower group.

[0015] The beneficial effects of the present invention are as follows:

[0016] The present invention combines the characteristics of air conditioning load changes, takes into account both the noise control and heat transfer performance of the heat source tower, has a wide range of applicability, and has great noise reduction potential and feasibility.

[0017] The noise requirements are considered at the initial stage of the design and selection of the heat source tower, avoiding subsequent noise reduction renovations, and having better system heat transfer performance and lower investment compared to traditional noise control measures such as sound absorption devices and sound insulation walls.

[0018] Other features and advantages of the present invention will be described in the subsequent specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a flow schematic diagram of the method of the present invention.

[0020] Figure 2It is the curve of the time ratio occupied by the building air-conditioning heat load rate in the embodiment of the present invention.

[0021] Figure 3 It is a schematic diagram of the relationship curve between the noise of the heat source tower and the air volume at the key monitoring points in the embodiment of the present invention. Specific embodiments

[0022] The following describes the specific embodiments of the present invention with reference to the accompanying drawings.

[0023] In this application, the heat source tower heat pump system is usually selected and configured according to the maximum air-conditioning load of the building. Under the real-time change of the building air-conditioning load, the system is in a partial load state for most of the time. Especially at night, the load of public buildings is smaller, and at this time, the noise requirements of the building surrounding environment are more stringent. This application fully considers the problems of whether the air volume change and heat transfer performance change caused by the variable speed of the fan can meet the air-conditioning load demand while reducing noise, and explores an active noise control method by regulating the operation of the heat source tower in combination with the characteristics of the air-conditioning load change, so as to balance the cost, heat transfer performance and the noise control requirements of the surrounding environment.

[0024] See Figure 1 , an active noise control method for a heat source tower heat pump system in this application includes two aspects: the design configuration of the heat source tower and the active regulation of the operation, specifically including:

[0025] Preliminarily set the design selection of the heat source tower and the number of units of the heat source tower group according to the air-conditioning cooling and heating design load;

[0026] Establish a noise model of the heat source tower, conduct numerical simulation calculations on the flow field of each heat source tower at the rated air volume, as well as the noise superposition and propagation of the heat source tower group, set key monitoring points, and evaluate whether the noise value at the key monitoring points meets the daytime noise standard, including: if not, adjust the design selection of the heat source tower and increase the number of heat source towers, and re-conduct numerical simulation calculations until the noise value corresponding to the set design selection and number of heat source towers meets the daytime noise standard (the daytime noise standard is usually higher than the nighttime noise standard);

[0027] Conduct noise superposition and propagation simulation calculations on the finally set heat source tower group at different air volumes, obtain the relationship curve graph between the noise value and the air volume of the heat source tower at the key monitoring points, and determine the maximum air volumes of the heat source tower group that meet the daytime and nighttime noise standards respectively;

[0028] Establish a heat and mass transfer model of the heat source tower, obtain real-time air-conditioning load and weather parameters, conduct heat and mass transfer simulation on each heat source tower, and under the limitation of the maximum air volume, conduct regulation of the operation parameters of the heat source tower. During the regulation process, select a set of operation parameters, and the temperature difference between the inlet solution temperature and the inlet air temperature corresponding to this set of operation parameters is the smallest, that is, obtain the best operation parameters for noise control.

[0029] Evaluating whether the noise value at the key monitoring point meets the daytime noise standard further includes:

[0030] If it does not meet the standard, adjust the design selection of the heat source tower and increase the number of heat source towers, and re-perform numerical simulation calculations. If the design selection and the number of towers of the heat source tower have reached the best selection considering economy and still cannot meet the daytime noise standard, then increase the solution flow rate of the heat source tower to reduce the temperature difference between the solution inlet and outlet, increase the heat exchange temperature difference between the solution and the air, and at the same time reduce the air volume, so as to reduce noise while meeting the heat exchange requirements and meet the daytime noise standard.

[0031] The method of the present application combines the characteristics of air-conditioning load changes, and through the operation control of the heat source tower heat pump system, actively controls the noise of the heat source tower to meet the requirements of the surrounding environment, while achieving better system heat exchange performance and lower investment.

[0032] The following further describes the technical solution of the present application with specific embodiments.

[0033] A method for actively controlling the noise of a heat source tower heat pump system in this embodiment includes the following steps:

[0034] Step 1: Initially set the design selection and the number of units of the heat source tower according to the air-conditioning cooling and heating design load;

[0035] Step 2: Establish a noise model of the heat source tower, perform numerical simulation calculations on the flow field of each heat source tower under the rated air volume, as well as the noise superposition and propagation of the heat source tower group, set key monitoring points, and evaluate whether the noise value at the key monitoring points meets the daytime noise standard, including: if it does not meet the standard, adjust the design selection of the heat source tower and increase the number of heat source towers, and re-perform numerical simulation calculations until the noise value corresponding to the set design selection and the number of heat source towers meets the daytime noise standard (the daytime demand is higher than that at night);

[0036] Among them, the numerical simulation calculation includes:

[0037] Establish a fluid domain of the heat source tower in the CFD software according to the structural parameters of the heat source tower such as tower length, tower width, tower height, air duct height, air duct diameter, number of blades, blade angle, blade chord length, hub diameter, impeller diameter, tip clearance, and blade thickness, and establish a three-dimensional solid model of the fan according to the fan blade parameters. The fluid domain includes a rotating domain set for the air duct area around the fan blades and a stationary domain set for the tower body part, and data is transmitted between the regions through the interface. Mesh the fluid domain, and increase the mesh density of the rotating domain close to the fan blades.

[0038] Combined with the above structural parameters, establish a heat source tower noise model as:

[0039]

[0040] In the above formula, p' is the far-field sound pressure, ρ0 is the density of the undisturbed air medium, ρ is the air density, a0 is the undisturbed sound speed, u i is the fluid velocity component in the x i direction, u n is the fluid velocity component perpendicular to the surface of f = 0, v n is the normal component of the moving object velocity on its surface, T ij is the Lighthill stress tensor, P ij is the compressive stress tensor, H(f) is the Heaviside function, and δ(f) is the Dirac function. f = 0 represents a mathematical surface that "embeds" the external flow problem (f > 0) in an unbounded space. The surface (f = 0) corresponds to the source (emission) surface and can coincide with the body (impermeable) surface or the permeable surface outside the body surface. n j is the unit normal vector pointing to the external region (f > 0).

[0041] Perform noise simulation of the heat source tower under the rated air volume to obtain the flow field information, and calculate the aerodynamic noise spectrum information of the heat source tower fan through the FW-H model. Specifically, it includes: drawing the position distribution of multiple heat source towers in the noise prediction software, setting the fan of the heat source tower as the noise source, and inputting the noise spectrum at the sound source, and then the noise values propagated at different distances after the noise superposition of multiple heat source towers can be simulated and calculated.

[0042] Set the position of the heat source tower group closest to the nearby human production and living areas as the key monitoring point, and obtain the noise value of the heat source tower at the key monitoring point. This noise value needs to meet the daytime noise standard, that is, it needs to be lower than the daytime environmental noise limit value in the area where the heat source tower is located.

[0043] When the noise value at the key monitoring point does not meet the daytime noise standard, adjust the type selection of the heat source tower and reduce the air volume and noise of a single heat source tower by increasing the number of heat source towers.

[0044] If the design type selection and the number configuration of the heat source tower have reached the best selection considering economy, but still cannot balance the noise and heat exchange requirements, then adopt the method of increasing the solution flow rate and reducing the air volume until the daytime noise standard is met.

[0045] By increasing the solution flow rate and reducing the air volume at the same time, the temperature difference between the solution inlet and outlet can be reduced, and the heat exchange temperature difference between the solution and the air can be increased to ensure the heat exchange requirements while reducing the noise. At this time, the heat exchange efficiency is slightly reduced, but according to the curve of the time ratio occupied by the building air-conditioning heat load rate, such as Figure 2As shown, the duration corresponding to a building heat load of 1 is relatively low, that is, the operation time under full load is extremely short. Therefore, only by reducing part of the performance in a short time can the air-conditioning load requirements and environmental noise standards be met simultaneously.

[0046] Step 3: According to the finally determined heat source tower type selection and number of units, perform variable air volume noise simulation on the established heat source tower noise model to obtain the noise source spectrum information.

[0047] In this embodiment, the design type selections of each heat source tower are the same, and the air volume allocated to each heat source tower during simulation is the same. The variable air volume simulation is to simulate different inlet air volume conditions of the tower.

[0048] Step 4: According to the noise spectrum data, perform noise superposition simulation and noise distance propagation simulation of the tower group in the noise prediction software. Take the closest distance between the heat source tower and the human activity area as the key monitoring point for noise propagation simulation, and obtain the relationship curve of the noise at this monitoring point and the air volume, as Figure 3 shown. According to the daytime and nighttime noise standards in the area where the heat source tower is located, respectively determine the maximum air volume of the heat source tower group that meets the noise standards during the day and at night.

[0049] Step 5: Establish a heat and mass transfer model of the heat source tower according to the air flow rate, air inlet and outlet temperature and humidity, solution flow rate, solution inlet and outlet temperature, solution density and other parameters that can be considered:

[0050]

[0051] h a =c pv t a +(r+c pq t a )w a

[0052]

[0053]

[0054]

[0055] In the above formulas: m w is the mass flow rate of the solution, kg / s; c pw is the specific heat capacity at constant pressure of the solution, kJ / (kg·°C); tw is the solution temperature, °C; L is the length of the packing area, m; m a is the mass flow rate of air, kg / s; h a is the enthalpy value of air, kJ / kg; H is the height of the packing area, m; h is the heat transfer coefficient, kW / (m 2 ·°C); W is the width of the packing; α is the specific surface area of the packing, m2 / m 3 ; r is the latent heat of vaporization, kJ / kg; c pq is the specific heat capacity of water vapor at constant pressure, kJ / (kg·°C); t a is the air temperature, °C; w a is the moisture content of air, kg / kg; h m is the mass transfer coefficient, kg / (m 2 ·s); w s is the moisture content of the solution surface boundary layer, kg / kg; c pv is the specific heat capacity of air at constant pressure, kJ / (kg·°C); P0 is the atmospheric pressure, Pa; P s is the partial pressure of water vapor on the solution surface, Pa; X s is the mass concentration of the solution.

[0056] Step Six: Obtain the real-time air-conditioning load and weather parameters of the heat source tower, conduct heat and mass transfer simulation on the heat source tower, and under the above maximum air volume limit, adjust the operating parameters of the heat source tower to obtain the operating parameters corresponding to the minimum heat exchange temperature difference between the solution and air (the temperature difference between the inlet solution temperature and the inlet air temperature), which are the optimal operating parameters, including operating parameters such as the air volume and water temperature of the heat source tower.

[0057] Specifically, use the feature recognition method to solve the parameters of the heat source tower heat transfer model, and determine the operating control parameters of the heat source tower through simulation.

[0058] In this embodiment, the heat source towers are of the same type, so the adjustment of the operating parameters of each heat source tower is kept consistent.

[0059] The active noise control method for the heat source tower heat pump system in this embodiment, combined with the characteristics of air-conditioning load changes, enables the improvement of heat exchange performance while meeting the load requirements and noise limits. It has better system heat exchange performance and lower investment compared with traditional noise control measures such as sound absorption devices and sound insulation walls, and has a wide range of applicability, providing a new way and method to solve the noise problem of the heat source tower through operation control.

[0060] Those of ordinary skill in the art can understand that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An active noise control method for a heat source tower heat pump system, characterized in that Including: Preliminarily set the design selection of the heat source tower and the number configuration of the heat source tower group according to the cooling and heating design load of the air conditioner; Establish a noise model of the heat source tower, conduct numerical simulation calculations on the flow field of each heat source tower under the rated air volume, as well as the noise superposition and propagation of the heat source tower group, set key monitoring points, and evaluate whether the noise value at the key monitoring points meets the daytime noise standard, including: if not, adjust the design selection of the heat source tower and increase the number of heat source towers, and re-conduct numerical simulation calculations until the noise value corresponding to the set design selection and number of heat source towers meets the daytime noise standard; Conduct noise superposition and propagation simulation calculations on the finally set heat source tower group under different air volumes, obtain the relationship curve between the noise value and the air volume of the heat source tower at the key monitoring points, and determine the maximum air volumes of the heat source tower group that meet the daytime and nighttime noise standards respectively; Establish a heat and mass transfer model of the heat source tower, obtain real-time air-conditioning load and weather parameters, conduct heat and mass transfer simulations on each heat source tower, and under the limitation of the maximum air volume, adjust the operating parameters of the heat source tower. During the adjustment process, select a set of operating parameters, and the temperature difference between the inlet solution temperature and the inlet air temperature corresponding to this set of operating parameters is the smallest, that is, obtain the optimal operating parameters for noise control.

2. The active noise control method for a heat source tower heat pump system according to claim 1, wherein The evaluation of whether the noise value at the key monitoring points meets the daytime noise standard also includes: If not, adjust the design selection of the heat source tower and increase the number of heat source towers, and re-conduct numerical simulation calculations. If the design selection and number configuration of the heat source tower have reached the best selection considering economy and still cannot meet the daytime noise standard, then adopt the method of increasing the solution flow rate of the heat source tower and reducing the air volume until the daytime noise standard is met.

3. The active noise control method for a heat source tower heat pump system according to claim 1, wherein The numerical simulation calculations on the flow field of each heat source tower, as well as the noise superposition and propagation of the heat source tower group, include: Use CFD software to conduct numerical simulation of the flow field of the heat source tower to obtain flow field information, obtain the aerodynamic noise spectrum information of the heat source tower through the FW-H model, and use noise prediction software to conduct noise propagation simulation and superposition simulation on the heat source tower group.

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