📚 Case Study Practice: Solar-Powered Irrigation System | 案例分析实战演练：太阳能灌溉系统
Engineering is about solving real-world problems. In this case study, we will explore the engineering design process by tackling a challenge faced by many rural communities: providing water for crops using renewable energy. You will step into the role of an engineer to design a solar-powered irrigation system.
工程学就是解决现实世界的问题。在这个案例研究中，我们将通过应对许多农村社区面临的挑战——利用可再生能源为作物提供灌溉用水——来探索工程设计过程。你将扮演工程师的角色，设计一个太阳能灌溉系统。
1. Understanding the Problem | 理解问题
Our target is a remote village with no access to the electrical grid. Farmers rely on rain, but dry seasons cause crop failure. They need a reliable way to pump water from a nearby river to irrigate fields. The system must operate during daylight hours using solar energy.
我们的目标是一个没有电网接入的偏远村庄。农民靠雨水耕作，但旱季导致作物歉收。他们需要一种可靠的方法从附近的河流抽水灌溉农田。该系统必须在白天利用太阳能运行。
Key questions: How much water is needed each day? What is the height difference (head) from the river to the fields? What are the average solar conditions? Answering these defines the problem scope.
关键问题：每天需要多少水？从河流到农田的高度差（扬程）是多少？平均日照条件如何？回答这些问题就确定了问题的范围。
2. Stakeholder Needs and Constraints | 利益相关者需求与限制
We must consider the farmers (the users), the village leader, and the local environment. Farmers need a system that is simple to operate and maintain. The design must be affordable, using locally available materials. Environmental constraints include protecting the river ecosystem.
我们必须考虑农民（用户）、村长和当地环境。农民需要一个操作简单、易于维护的系统。设计必须经济实惠，使用当地可获得的材料。环境限制包括保护河流生态系统。
Constraints: budget of US$500, daily water delivery of 2000 litres, and pump head of 10 metres. The system must be robust and have a lifespan of at least 5 years with minimal maintenance.
限制条件：预算500美元，日供水量2000升，水泵扬程10米。系统必须坚固，使用寿命至少5年，维护量最小。
3. Researching Existing Solutions | 调研现有解决方案
We research existing irrigation pumps: diesel pumps (polluting, expensive fuel), manual treadle pumps (labour-intensive), and solar pumps. Solar irrigation pumps already exist, but many are designed for larger farms. We can learn from their components: solar panels, charge controller, battery (optional), and DC pump.
我们调研现有的灌溉水泵：柴油泵（污染、燃料昂贵）、脚踏泵（劳动密集）和太阳能泵。太阳能灌溉泵已经存在，但许多是为大型农场设计的。我们可以从它们的组件中学习：太阳能板、充电控制器、电池（可选）和直流泵。
We discover that using a direct-drive solar pump without batteries is cheaper and simpler. However, it only works when the sun shines. This trade-off must be evaluated against crop watering schedules.
我们发现使用不带电池的直接驱动太阳能泵更便宜、更简单。但是，它只在阳光明媚时工作。必须根据作物灌溉时间表评估这一权衡。
4. Defining Design Specifications | 定义设计规格
rray. It should operate in full sunlight (solar irradiance ≥ 800 W/m²) for at least 5 hours/day. The pump flow rate should be at least 0.5 litres per second.
根据调研，我们撰写设计规格：系统必须每天输送2000升水，克服10米扬程，使用光伏阵列。应在充足日照下（太阳辐照度≥800瓦/平方米）每天至少运行5小时。水泵流量应至少为0.5升/秒。
We also specify that the system must be portable, with a maximum weight of 40 kg, and must include a simple control unit to prevent dry running. The cost of components must not exceed $500.
我们还规定系统必须便携，最大重量40千克，并且包含一个简单的控制单元以防止干转。部件成本不得超过500美元。
5. Brainstorming Possible Designs | 头脑风暴设计方案
We generate three concepts: (A) A submersible solar pump placed directly in the river, powered by a fixed solar panel. (B) A surface pump mounted on the bank, with a suction hose, powered by a tracking solar panel. (C) A floating pump unit with integrated PV panel, eliminating the need for a long power cable.
我们产生了三个概念：(A) 一个直接放置在河中的潜水泵，由固定式太阳能板供电。(B) 一个安装在岸上的地面泵，带吸水管，由跟踪式太阳能板供电。(C) 一个集成光伏板的浮动泵单元，无需长电缆。
We sketch each idea, noting pros and cons. Concept A is simplest but risks damage from floods. Concept B requires a strong foundation. Concept C is innovative but may be difficult to build with local resources.
我们勾画每个想法，记录优缺点。概念A最简单，但有洪水损坏的风险。概念B需要坚固的基础。概念C创新，但可能难以用当地资源建造。
6. Evaluating and Selecting the Best Idea | 评估与选择最佳方案
We use a decision matrix to score concepts against criteria: cost, ease of construction, reliability, efficiency, and maintainability. Each criterion is weighted. Concept A scores highest due to low cost and simplicity. We select it for development.
我们使用决策矩阵，根据成本、建造容易度、可靠性、效率和可维护性等标准对概念打分
Published by TutorHao | Year 8 工程 Revision Series | aleveler.com
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