[EL] [Renew./Inno.] 問﹕Lift / Elevator 响設計上有啲乜要留意？

答﹕

首先係揀 lift, 主要有三種

有機房Lift (Traction, 拖帶，平時最常見)

無機房Lift (Traction, 慳返間Lift機房，則師最鐘意，但要留意唔係完全冇晒，個頂一樣有啲嘢；而且慳電)

油壓Lift (Hydraulic, 特點係慢，真係好慢，高度有限制，極限幾層樓； 同時可負好重既重量，地鐵站經常見到有用到，或停車場載車)

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之後就根據Rule of thumb 大概預四、五層樓就要一部Lift

再之後就要根據CIBSE Guide D 入機進行精確啲既估算

有兩個重要概念一定要知﹕

5 mins handling capacity 五分鐘裡面，可以載走整棟大樓幾多人。如成棟樓800人, 5 mins handling capacity is 15%, 即係可載走120人。大概預 11-15%
Interval
Travelling Time=Round Trip Time/電梯數量，大概預30s

*Round Trip Time: 一部lift 由地下行完棟樓一圈再返落樓下開門既時間

仲有啲林審嘢要留意，如Car fill factor: 一部16 人Lift未必裝得滿16人，可能得14人；Builder related e.g. lift core requirements, overhead / lift pit size, travel distance etc.

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Innovative 啲既設計﹕

Hall Call Allocation - 即係電腦系統會自動派部LIFT比你

Double Deck - 一個lift car 裡面有兩層

Energy reclaim (EMSD) - Regenerate 返啲電比其他Lift, 重load向下及輕Load Counter Weight 向下個效果會明顯啲

Variable Voltage Variable Frequency VVVF - 通過同時調整Voltage & Frequency, 可以响加速及減速期間降低個Current從而達至Energy Saving.

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Lift T&C and Inspection

Safety Related:
- Over speed governors test; - Safety Break;
- Overload Test;
- Lift door mechnical interlock;

Electrical Related:
- Apparent Power, Total Harmonic Distortion 量度; - Reverse phase, Phase loss (反相，缺相) Test;

Builder Related: - 部LIFT停响最頂嗰層既時候，度 over run 距離； 記咗堆safety components, 因為實要Inspection呢堆嘢

做好晒，行完慢車(比正常慢既速度)嚟試行部LIFT，一切準備就緒，就可以入Form 5 叫EMSD班人嚟驗LIFT
成功驗LIFT後，EMSD 會出一張叫"Use Permit", 你部LIFT就可以正式使用

Fireman Lift係用FSI Genset backup; Non-fireman lift sequential homing用Non FSI Genset backup. 當然一樣可以用FSI Genset嚟backup, 咁就要比FSD批，詳見 https://elvissharing.blogspot.com/2020/03/el-fs-genset.html
Lift Supervisory System都有機會用UPS嚟頂一陣， Say 15mins.

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無機房Lift嘅Lift Shaft 風扇計算﹕

把扇有四個條件係要滿足﹕

1. 足夠MRL 個摩打嘅散熱量；

2. 把扇有兩段控速或以上；

3. 把扇可維持五度至四十度；

4. 把扇做到10ACH for machine room or machinery space at the top of the well and its associated working space for machine room-less lift;

要求1.係要滿足Lift佬；而要求2., 3., 4.係要滿足EMSD嘅Code of Practice on the Design and Construction of Lifts and Escalators, 要留意，呢本嘢係冇得免費下載，以下係部份內容嘅截圖﹕

假設Lift佬嘅摩打散熱要求係1580kcal/h, 我地首先要搵返究竟係幾多個kW, 其實只要用一啲簡單嘅字眼响google search, e.g."kcal to kW online convertor", 就可以搵到點轉，如呢個 huansuan-danwei.info , 即時知道1580kcal/h=1.84kW:

之後我地就用中學會考物理嘅E=mc△T嚟計，為咗易計啲，將條公式兩邊同時除second, 咁就變成 Q = airflow rate * specific heat of air * △T;

而density of air = mass flow rate / volume flow rate, 我地最終目的係要搵個volume flow rate出嚟，成條式reform完就變成﹕

V = Q/ (cp)(△T)(d)

V = airflow rate; (m3/s)

Q = Total heat emitted; (kW)

cp = Specific heat of Air; (1.01 kJ/kg/oK)

△T = Genset room temperature rise; (oK), 跟據EMSD CoP, 最高溫度係40, 假設吹入lift shaft散熱嘅風係由室外吹入去，跟據BEEO 2018, outdoor design temperature 係35度，即係(40-35)=5

d = Density of air (1.20 kg/m3)

V = 1.84/(1.01*1.2*5) = 0.304m^3/s

之後就要先搵個static出嚟，搵風扇也好，泵也好，Static+Flow Rate係必備。假設Lift shaft 係2.9m x 5.2m x 53.2m(H), 頂同底有兩個0.3 meter square嘅louver, 咁個static應該點計？

首先假設咗成條lift shaft係一條石屎風喉；由於條shaft太大以致唔可能由CIBSE Guide C搵到送風嘅有效面積，所以一般會以橫切面嘅方形畫到最大嘅圓形直徑嚟估算，即係2.9m. 之後我地再用google大神search "concrete duct friction loss calculator"類似字眼，就會搵到大量嘅online calculator, 就以 Good Calculators 為例子，輸入晒數據就可以發現，原來呢個風量嘅情況下，個pressure drop (or say friction loss) 係可以ignore:

再之後估算一個louver個pressure drop有幾多，一般顧問會say落去如10-50Pa; 又或者可以大概計下，都係可以用google大神search "louver pressure drop calculator" or "louver pressure catalogue": 

Air volume flow rate, louvre area等數都有(留意係入個有效面積，即係如果係一個0.3m x 1m = 0.3meter square嘅builder窿，一般係會take返0.5 efficiency, 即係0.15 meter square); 而個discharge loss coefficient 可以搵啲類似嘅catalogue攞返個數。計完之後，見到個pressure大概係17Pa, 一上一下兩個louvre即係34Pa.

最後要check埋把扇達唔達到"10ACH for machine room or machinery space at the top of the well and its associated working space for machine room-less lift"要求，一般係lift shaft overrun嘅volume除一個鐘頭嘅秒數3600, 設overrun為5m

2.9m x 5.2m x 5m x 10 / 3600 = 0.209m^3/s

0.304m^3/s > 0.209m^3/s，所以係滿足得埋條件4.所要求嘅10ACH.

之後就可以去catalogue揀風扇﹕

為咗滿足條件2.嘅要求，當然係要搵啲有兩段速以上嘅風扇。

(Source: 香港電梯資料網 hkelev.com)