集约化猪场通风与供热的理论及应用

Maximal rates 最大通风率
• • • • • During hot or very hot period: 在相对较热的时期： Evacuate the heat and the moisture emitted by the pigs 将猪只本身产生的热量排出室外 But when the outside temperature is high, the room temperature will be always greater, even with high flows of air = Introductions of the coolings systems • 但是当室外温度较高时，为了保证室内合适的温度， 需要加装湿帘等降温系统。
Natural ventiBaidu Nhomakorabeaation standards 适合自然通风的参数标准
• Maximum diameter of the air inlet • 0.2 m² per 1000 m3/hour allowed air • 进风口最大直径：0.2平方米，每小时进风 量1000立方米/小时。
• There are 3 large air inlet type: 进风口的类型有3种： Ceilings perforated or with diffusers • The sheaths • The side panels on the walls • 屋顶孔状垂直通风； • 侧墙风窗水平通风； • 鞘状通风。
• 进风口表面积越大，风速便会衰减的越快； • 进风口表面积越小，风速便会衰减的越慢。 • 例如：有两个风机的栋舍，每个风机的排 风量为7500立方米/小时，风速为3米/秒： • 我们将进风口的表面积设为X，那么我们得 到等式： 15000立方米/小时=X平方米*3米/秒*3600 经过计算，X=1.4平方米，即进风口的表面积 应为1.4平方米。
A few rules of physics 几点物理学原理
• In an air circuit, it comes always back to equilibrium: what enters equal to what emerges: If a parameter gene entry or exit in the circuit ,all the flow will be reduced • 在空气循环中遵循着一定的守恒定律，有多少空气进入， 就会有多少空气排出，一旦有某项参数发生变化，则整 个风量也会发生变化。 • Warm air rises because it is light instead of cold air coming down because its mass is more important (presence of water) 相对于冷空气来说，热空气总是向上流动，因为质量较 轻，而冷空气则向下流动，因为质量较重（含有水分）。
The ventilation systems 通风系统
• 1 natural ventilation, controlled or not • 1. 自然通风 • In winter the draw is done by the difference of temperature between the building and the outside: the hot air is expelled naturally through openings in the roof and fresh air back by side panels located on the walls of the building • 在冬天，自然通风是通过室外和室内的温度差异来实现 的，室内的热空气通过屋顶开口排出，同时新鲜的空气 通过室内侧面的墙壁的小孔进入 • In summer, the ventilation is provided by the side flaps und er the effect of wind (wind regular directions need) • 夏天，空气从墙壁侧面通风窗进入（但是风向需要恒定）
• On the basis of these requirements so there for each physiological stage animals, minimums and maximums of ventilation 在这些要求的基础上，结合动物不同的生 理阶段，需要设置最小和最大通风率。
Air inlets 进风口
• 1 the buildings air intakes: • 1. 楼层进风口： • They must be large enough to avoid braking of the incoming air otherwise slowdown the performance of fans: • 进风口必须足够大，保证足够的风量和速度，进而保证风机的 正常运转。 For air inlets in the Gables of the buildings, the speed must not exceed 2.5 m/s • For air inlets located in the roofs or sheaths, the speed must not exceed 4 m/s • 如果进风口设置在侧墙，其风速不能超过2.5米/秒； • 如果进风口设置在屋顶，其风速不能超过4米/秒。
The ventilation 通风
• The ventilation is designed: • To bring new air to animals • Eliminate harmful gases • Remove the moisture produced by pigs • In summer: lower the temperature of pigs 通风设计的主要目的： 给室内动物输入新鲜的空气； 将室内有害气体排出室外； 将室内动物产生的湿气排出室外； 夏季：降低室内温度。
• Advantages: • Suitable premises with low density of animals • 优点：土建规格合适，动物生存密度低 Disadvantages: • Not possible on large groups of animals • Not possible if the slurry is stocked in pre pits under animals • 缺点：不适合大规模集约化动物养殖；不适合 水泡粪的养殖模式。
• • • • •
The ventilation by positive pressure 正压通风： Is interesting when the sealing of the building is difficult to achieve 正压通风在封闭不好的猪舍比较难以实现； Is mandatory in the units protected by air filtration, to prevent entrance of air unfiltered which might contaminate the animals. • 当我们需要对进入猪舍的空气进行过滤时，一般考虑施行正压通风， 来保证空气中的有害细菌和病毒感染到猪只。 • The ventilation by depression is by far the most used in pork production • 在大多数规模化养殖场采用的是负压通风。 • At every time when the minimum of ventilation: at least 25 Pascal and when maximum of ventilation 40 to 50 Pascals
150
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30
65
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35
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如何计算风量？
• Airflow depends on several variables: • The section input or output of the air in m2 • The speed air generally calculated in meters per second (m/s) 风量的计算取决于下面两个变量： 空气进入或排出口的表面积； 风速（米/秒） Air flow is calculated in m3/hour, it is therefore necessary to replace the m/s in meter per hour by multiplying by 3600 (3600 second within 1 hour) • Example: 1.4m2*3m/s*3600=15120m3/h • 风量是按照立方米/小时来计算的，因此我们在计算时应乘以 3600（一小时等于3600秒） • 例如：1.4平方米*3米/秒*3600=15120立方米/小时。
Minimal and maximal air need renewal by pig In m3/hour/animal
配种舍 最小风量 25
妊娠舍 25
产房 30
保育舍 8 (3 to 8)
育肥舍 公猪站 16 ( 8 to 25 16)
最大风量 （夏季较 热时期）
最大风量 （夏季非 常热的时 期）
• 2 air inlets in the rooms: • 2. 栏舍进风口： They are intended: To introduce the new fresh air in the room Ensure a homogeneous atmosphere at the level of the room temperature At the level of the air velocity 栏舍内进风口设置的目的：保证栏舍内新 鲜空气的进入，保证新鲜空气的均匀度和速率。
Working principle 工作原理
• Allow new air to mix properly in ambient air before slowly descending to the level of pigs • 在空气吹到猪只身体之前进行充分的混合 For this it is necessary to obtain a highspeed admission to create a loop of mixture between the two kind of air
Maximum diameter of the air outlet • -0.15 m² per 1000 m3/hour of air extracted
出风口最大直径：0.15平方米，每小时出风量 1000立方米/小时
The mechanic ventilation 机械通风
• The renewal of air is provided by a fan. • 通风是通过风机实现的。 • When this fan is situated at the entrance of the air supply and pushes air in the building, it is positive pressure ventilation • 如果风机安装在进风口，我们称之为正压通风。 • When the fan is positioned at the exit of the circuit of air and extract stale air, it is ventilation by depression 如果风机安装在出风口，我们称之为负压通风。
The minimum rates 最小通风率
• In adverse cold period: • 在相对较冷的时期： • Outside temperature of 0°C and 100% humidity • 室外温度达到0摄氏度，并且湿度达到100% • 保持二氧化碳和湿度在合理的范围内： • 二氧化碳：小于0.3%； • 湿度测定：小于75%