Ship living cabin airflow optimization analysis method

Abstract

The invention relates to a ship living cabin airflow optimization analysis method, which comprises the following steps of: constructing a geometric model of a cabin, and setting air inlet and outlet layout and wind speed parameters; through CFD simulation software, a Realizable k-epsilon turbulence model is used for simulating and calculating air flow in a ship living cabin, and air temperature, pressure, flow velocity and PMV and PPD thermal comfort evaluation indexes are analyzed in an emphasized manner; according to the simulation result, the thermal comfort degree of the ship living cabin can be evaluated, so that the layout of the ship living cabin is optimized in a targeted manner, the airflow organization of an air conditioning system is optimized, and it is ensured that the PMV value is between-1 and 1, and the PPD value is smaller than 20%; the air flow uniformity and the thermal comfort degree of the ship living cabin can be improved, the local retention airflow phenomenon is reduced, meanwhile, the operation efficiency of an air conditioning system is improved, and the energy-saving and emission-reducing effects are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of cabin airflow optimization, and in particular to a method for optimizing and analyzing airflow in a ship's cabin. Background Art

[0002] The air conditioning and ventilation system in the public areas of passenger ships is an important part of ensuring the comfort of the internal environment of the ship. Especially during long-term voyages, the thermal comfort of crew members and passengers has a key impact on the overall ship experience. With the improvement of living standards, people's requirements for indoor air quality and comfort are increasing. Especially on high-end ships such as luxury cruise ships, the efficient operation of their air conditioning systems is directly related to operating costs and passenger experience. Therefore, the design of energy-saving, efficient and passenger comfort-enhancing air conditioning systems has become a hot topic in current research.

[0003] At present, computational fluid dynamics (CFD) methods are mostly used to simulate and analyze indoor air flow in large-space buildings. However, there are relatively few studies on small ship cabin spaces, especially the study of airflow organization in luxury cruise cabins, which also has many limitations. Previous studies have mainly focused on the thermal environment and airflow organization of large spaces, and there are few studies on small spaces such as crew studios and cabins. In current simulation studies, there is a general challenge of accurately predicting air flow and thermal comfort in small enclosed spaces, especially in the selection of multiple turbulence models, which can easily lead to deviations in results. In addition, the complex geometric structure of ship cabins and the placement of various items make it difficult to optimize the distribution of airflow, and the problem of uneven air supply still exists, making it difficult to ensure the thermal comfort of passengers in the cabin.

[0004] In addition, the existing CFD simulation and analysis methods mostly use the system default RNG k-ε model, which is suitable for simulating general turbulent flows, but has certain limitations in dealing with flow fields in complex closed spaces. Especially in the case of high rotation and flow separation, the RNG model has low accuracy, which can easily lead to uneven flow field distribution and make it difficult to comprehensively improve the thermal comfort in the cabin. In addition, the calculation accuracy of the RNG model for turbulent energy dissipation is limited in small closed spaces, which makes the simulation results deviate from actual application requirements.

[0005] Based on this, there is a need for an airflow optimization analysis method that is particularly suitable for ship cabins. By analyzing the airflow organization in the ship cabins, the layout inside the cabin can be optimized and the thermal comfort of crew members and passengers can be effectively improved. Summary of the invention

[0006] The object of the present invention is to provide a method for optimizing and analyzing airflow in a ship's cabin, and the object of the present invention is achieved by the following technical solutions:

[0007] The present invention provides a method for optimizing and analyzing airflow in a ship cabin, which comprises the following steps:

[0008] S1. Determine the geometry of the simulation model, including the furniture layout, air inlets, air outlets, and lighting in the cabin;

[0009] S2. Use CFD software Airpak to build a simulation model of airflow in the ship's cabin;

[0010] S3, select the Realizable k-ε turbulence model, set the turbulence intensity, and calculate the distribution of airflow in the cabin;

[0011] The model constants and function expressions in the Realizable k-ε turbulence model are:

[0012]

[0013] C 1ε =1.44, C 1ε =1.9,σ k =1.0,σ ε =1.2;

[0014] S4. Focus on analyzing the thermal comfort of the cabin;

[0015] S5. Optimize the air conditioning and ventilation system by comparing the thermal comfort before and after optimization through simulation.

[0016] Preferably, in step S1, the size of the cabin simulation model is 7×5×3.5m; the parameters of the components in the cabin are set as follows: the wind speed of the air inlet is 1m / s, and the wind speed of the air outlet is 0.5m / s.

[0017] Furthermore, the cabin also includes three 35W light strips and two human heat sources, each with a power of 35W / m2.

[0018] Preferably, in step S2, a gas turbulent jet is used to construct a ship cabin airflow simulation model, and the gas turbulent jet includes a temperature difference jet and an attached jet in the cabin.

[0019] Preferably, one or more of the velocity, pressure and temperature of the gas turbulent jet is represented by the sum of an average value and a pulsation value.

[0020] Furthermore, in step S3, the turbulence intensity is set to 10%.

[0021] Preferably, in step S4, PMV is used as an evaluation index of thermal comfort, wherein the PMV value between -1 and 1 is in the comfortable range.

[0022] Furthermore, in step S4, the PPD value is also used to evaluate thermal comfort, and a PPD value less than 20% is within an acceptable range.

[0023] Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0024] First, the present invention uses the Realizable k–ε turbulence model to simulate and analyze the air conditioning and ventilation systems in public areas of passenger ships, and optimizes the layout design of the supply and return air vents. Compared with traditional air conditioning systems, the present invention can distribute the airflow more evenly and reduce the concentration or blank phenomenon of airflow in local areas, thereby improving the uniformity of the overall air flow and effectively improving the thermal comfort of passengers.

[0025] Second, the present invention uses PMV (Predicted Mean Vote) and PPD (Predicted Percentage of Dissatisfied) values ​​to evaluate the thermal comfort in the ship's cabin. The PMV value is maintained in the range of -1 to 1, and the PPD value is less than 20%, ensuring that most passengers feel comfortable during long voyages. Compared with traditional designs, the present invention optimizes the indoor air temperature and humidity distribution through simulation analysis, improving the living experience of passengers.

[0026] Third, the present invention optimizes the airflow organization of the air-conditioning system of the ship's cabin by targeted analysis of the gas turbulent jet in the ship's cabin, thereby reducing the power consumption of air supply while maintaining comfort; through reasonable airflow path design and turbulence model calculation, the high-energy airflow recirculation phenomenon is reduced, and the airflow speed control at the air outlet is improved, effectively reducing the energy consumption of the air-conditioning system and achieving the effect of energy saving and emission reduction; when dealing with complex geometric layouts in ship cabins (such as beds, cabinets, etc.), the simulation method of the present invention can accurately calculate the impact of different objects on airflow distribution; through reasonable airflow guidance and optimization, the air quality in the cabin is significantly improved, and the air stagnation phenomenon in the passenger ship cabin is reduced, which helps to improve the health and comfort of the overall environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 A cloud map of a three-dimensional perspective of a ship's living cabin according to the first embodiment of the present invention;

[0029] Figure 2 A three-dimensional top view of a ship's living cabin according to a first embodiment of the present invention;

[0030] Figure 3 A cloud map of a ship's cabin from a three-dimensional perspective according to a second embodiment of the present invention;

[0031] Figure 4 A three-dimensional top view of a ship's living cabin according to a second embodiment of the present invention;

[0032] Figure 5 The present invention is a flow chart of the ship cabin airflow optimization analysis method.

[0033] Description of Reference Numerals

[0034] 1. The bathroom is equipped with a fan; 2. Side air vents. DETAILED DESCRIPTION

[0035] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0036] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0037] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is only illustrative. Based on the present invention, it should be understood by those skilled in the art that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method. In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that it can be practiced without these specific details; it should be understood that the embodiment of this specification is only preferred with the airflow optimization of the air conditioning system in the ship's cabin as the specific analysis object, and cannot be understood as a limitation of the independent claims of the present invention.

[0038] In the existing technology, if the airflow distribution around the simulated person in the ship's cabin is unreasonable, the comfort level cannot meet certain requirements. There is no suitable analysis method to conduct targeted analysis of the airflow in the ship's cabin. It is difficult to accurately predict the challenges of air flow and thermal comfort in a small enclosed space, especially in the selection of multiple turbulence models and the simulation of the human body, which can easily lead to deviations in the results.

[0039] Based on this, the embodiments of this specification provide a method for optimizing and analyzing airflow in ship cabins, thereby achieving some optimizations in the adjustment and air supply conditions in the ship cabins, including some optimizations in comfort and an improvement in the experience.

[0040] Embodiment 1:

[0041] This embodiment provides an airflow optimization analysis method for an air conditioning system in a ship's cabin, and the process is as follows: Figure 5 As shown, the specific steps are as follows:

[0042] S1: The public area in the ship's cabin is selected as the research object. The model size of the ship's cabin is 7×5×3.5m. The structure and contents and properties of the items in the ship's cabin are as follows: the heat of each light is 35W, there are three lights in total, the size of the character model is 1.75m, there are two people sitting on two beds respectively, and each person generates 35W / m 2 , the air intake fan in the living room, the air outlet velocity is assumed to be 1m / s, and the air inlet size is r = 20cm, so the calculated volume flow rate is 0.126m 3 / s. Similarly, assuming the size of the bathroom fan is r = 20cm, and the air outlet velocity is assumed to be 0.5m / s, the calculated volume flow rate is 0.063m 3 / s; The length and width of the three vents in the room are 50×30cm.

[0043] The gas turbulent jet simulation is adopted in the ship's cabin, which belongs to the temperature difference jet and attached jet in a limited space. When the air is supplied from the air outlet, the temperature generally has complex flows such as vortex separation, merging, and meandering. The air supply speed of the air outlet is generally 2-5m / s, and the flow rate is relatively low; when the air supply speed is large, jet impact may occur; at the same time, when the jet is attached, the Coanda effect has a great influence on the air flow field distribution. In addition, due to the complex geometric structure and type layout in the living cabin, such as bed, wardrobe, coffee table, desk, wardrobe, air outlet, return air outlet, etc., the flow field model is selected as an important node; the geometric model is established in the CFD simulation software, which accurately simulates the geometric structure and the placement of items in the ship's cabin.

[0044] In this scheme, since the gas turbulent jet is a highly complex three-dimensional non-steady-state, irregular flow with rotation; the physical parameters of the fluid in the gas turbulent jet, such as velocity, pressure, temperature, etc., change randomly with time and space; in the turbulent flow field, the random motion of the fluid particles obeys certain mathematical statistical laws over a sufficiently long time; any instantaneous physical quantity in space can be expressed by the sum of the average value and the pulsation value. The main reason for using this method is that the instantaneous value of each physical quantity is random, which makes theoretical research encounter many difficulties. After using the above decomposition, it can be assumed that the flow is quasi-steady in most cases, and the statistical average method can be used to numerically solve the flow equation; and in experimental research, it is more difficult to determine the instantaneous value of each physical quantity, while it is easier to determine the time average value.

[0045] Continuity equation:

[0046]

[0047] Momentum equation:

[0048]

[0049] S2: Set the positions of air inlets and air outlets in the ship's cabins. The air inlet is designed as a circular air outlet with a diameter of 20 cm, and the air inlet speed is set to 1 m / s; the air outlet is designed as a circular air outlet with a diameter of 16 cm, and the air exhaust speed is set to 0.5 m / s; the air outlets are arranged on opposite sides of the room to ensure that the air can be evenly distributed throughout the ship's cabin; the wind speed and air outlet position are optimized according to the actual needs in the ship's cabin to ensure the uniformity of air flow and avoid airflow dead corners and excessive wind speed.

[0050] S3: In the CFD simulation analysis, turbulence is determined by objects in the Airpak model, and the Realizable k-ε model is selected; the turbulence intensity used in this model is set to 10%, and the turbulence length scale is the default value.

[0051] The model constants and function expressions in the Realizable k-ε turbulence model are:

[0052]

[0053] C 1ε =1.44, C 1ε =1.9,σ k =1.0,σ ε =1.2.

[0054] In this scheme, the Realizable-ε model is used to analyze the airflow in the ship's cabin. The Realizable-ε model provides swirl and curvature correction, and has good calculation accuracy and adaptability for phenomena such as rotating flow and flow separation. The model has good advantages in free stream jet and mixing layer, cavity flow, boundary layer flow, and shear flow calculation. In particular, the Realizable-ε model can give a fairly good jet expansion in the simulation of circular jet and flat plate jet, which is suitable for the characteristics of the ship's cabin in this embodiment.

[0055] S4: Through simulation, key parameters such as air temperature, pressure, and flow rate in the ship's cabins are calculated, and two evaluation indicators, PMV and PPD, are introduced to analyze the thermal comfort of the ship's cabins; the PMV value is within the comfortable range of -1 to 1, indicating that the environment is suitable for living; the PPD value is used to measure the proportion of passengers in the ship's cabins who are dissatisfied with the environment, and the PPD value should be controlled below 20%.

[0056] In a preferred embodiment, Figure 1 and Figure 2 As shown, this embodiment only uses the PPD index to evaluate the thermal comfort of the ship's cabin; the PMV index is more applicable in an air-conditioned environment that is close to a thermal comfort environment, and the result is more accurate, but for a non-air-conditioned environment, there may be a large deviation; due to the complexity of the PMV thermal comfort model establishment process and the influence of individual differences and adaptability of experimenters on subjective judgment, they will become the source of environmental thermal comfort prediction deviation.

[0057] Embodiment 2:

[0058] like Figure 3 As shown, compared with Example 1, this Example 2 adds two side vents in the ship cabin, rearranges and discharges important components such as indoor lights, reduces the diameter of the bathroom fan 1 from r=20cm to 16cm, and adds side vents 2 with a length of 60cm on both sides of the ship cabin. In the object determination turbulence in the Airpak model, the improved ship cabin calculation model uses the Realizable k-ε model, and the values ​​of the turbulence intensity and turbulence length scale follow the default value parameters of the system without change. The simulation shows that the air distribution is more reasonable, especially in the bedroom and office area, the airflow organization has been significantly improved.

[0059] In a preferred embodiment, only the PMV index is used to evaluate the thermal comfort of the ship's cabin. The PMV index is more applicable in an air-conditioned environment close to a thermal comfort environment, and the result is more accurate, but for a non-air-conditioned environment, there may be a large deviation.

[0060] In this scheme, by changing the layout of the ship's cabins, the airflow distribution diagram and various values ​​output by the simulation software verified that the performance of the air conditioning and ventilation system has been optimized; Figure 3 and Figure 4 The simulation results show that Figure 3 The PPD values ​​of the ship's cabins are unevenly distributed, and there may be more high-value areas, indicating that the airflow organization at this time cannot cover the entire cabin space well, resulting in insufficient comfort in some local areas; Figure 4 The PPD value in each area is reduced, indicating that the optimized air-conditioning system has successfully improved the air flow distribution, making the temperature, wind speed and other indicators in the cabin more in line with the human comfort requirements, thereby reducing the proportion of uncomfortable people; the PPD value of the ship cabin after optimization is significantly reduced, which greatly improves the uniformity of air flow, reduces the local air stagnation phenomenon, and effectively reduces the air flow impact felt by passengers, increasing the overall comfort; at the same time, by improving the air outlet layout, the invalid air flow recirculation phenomenon is reduced, thereby improving the operation efficiency of the air-conditioning system; the simulation results show that the improved ship cabin can effectively reduce the overall energy consumption and achieve energy-saving effects. Therefore, the air conditioning airflow optimization analysis method of the ship cabin of this embodiment can effectively analyze the airflow in the ship cabin and improve its layout in a targeted manner.

[0061] In this specification, the same or similar parts between the various embodiments may refer to each other, and each embodiment focuses on the differences from other embodiments; in particular, for the embodiments described later, the description is relatively simple, and the relevant parts may refer to the partial description of the aforementioned embodiments.

[0062] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for optimizing and analyzing airflow in a ship's cabin, characterized in that: The following steps are involved: S1. Determine the geometry of the simulation model, including the furniture layout, air inlets, air outlets, and lighting in the cabin; S2. Use CFD to build a simulation model of airflow in the ship's cabin; S3, select the Realizable k-ε turbulence model, set the turbulence intensity, and calculate the distribution of airflow in the cabin; The model constants and function expressions in the Realizable k-ε turbulence model are: C 1ε =1.44, C 1ε =1.9,s k =1.0,σ ε =1.2; S4. Focus on analyzing the thermal comfort of the cabin; S5. Optimize the air conditioning and ventilation system by comparing the thermal comfort before and after optimization through simulation.

2. The ship cabin airflow optimization analysis method according to claim 1 is characterized by: In step S1, the size of the cabin simulation model is 7×5×3.5 meters; the parameters of the components in the cabin are set as follows: the wind speed of the air inlet is 1 m / s, and the wind speed of the air outlet is 0.5 m / s.

3. The ship cabin airflow optimization analysis method according to claim 2 is characterized by: The cabin also includes three 35W light strips and two human heat sources, each with a power of 35W / m2.

4. The ship cabin airflow optimization analysis method according to claim 1, characterized in that: In step S2, a gas turbulent jet is used to construct a ship cabin airflow simulation model, and the gas turbulent jet includes a temperature difference jet and an attached jet in the cabin.

5. The ship cabin airflow optimization analysis method according to claim 4 is characterized by: One or more of the velocity, pressure and temperature of the gas turbulent jet is represented by the sum of an average value and a pulsation value.

6. The ship cabin airflow optimization analysis method according to claim 1, characterized in that: In step S3, the turbulence intensity is set to 10%.

7. The ship cabin airflow optimization analysis method according to claim 1, characterized in that: In step S4, PMV is used as an evaluation index of thermal comfort, and the PMV value between -1 and 1 is a comfortable range.

8. The ship cabin airflow optimization analysis method according to claim 7 is characterized by: In step S4, the PPD value is also used to evaluate the thermal comfort, and the PPD value is within an acceptable range if it is less than 20%.

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