engineering

Thermal manikin

Thermal manikin is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Thermal manikin rather than just read about it. In short: The thermal manikin is a human model designed for scientific testing of thermal environments without the risk or inaccuracies inherent in human subject testing. Thermal manikins are primarily used in automotive, indoor environment, outdoor environment, military and clothing research.

Key takeaways

Thermal manikin belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Thermal manikin to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Thermal manikin from memory before moving on to harder problems.

Reference excerpt

The thermal manikin is a human model designed for scientific testing of thermal environments without the risk or inaccuracies inherent in human subject testing. Thermal manikins are primarily used in automotive, indoor environment, outdoor environment, military and clothing research. The first thermal manikins in the 1940s were developed by the US Army and consisted of one whole-body sampling zone. Modern-day manikins can have over 30 individually controlled zones. Each zone (right hand, pelvis, etc.) contains a heating element and temperature sensors within the “skin” of the manikin. This allows the control software to heat the manikin to a normal human body temperature, while logging the amount of power necessary to do so in each zone and the temperature of that zone.

History Clothing insulation is the thermal insulation provided by clothing and it is measured in clo. The measuring unit was developed in 1941. Shortly afterward, thermal manikins were developed by the US Army for the purposes of carrying out insulation measurements on the gear they were developing. The first thermal manikins were standing, made of copper, and were one segment, measuring whole-body heat loss. Over the years these were improved upon by various companies and individuals employing new technologies and techniques as understanding of thermal comfort increased. In the mid-1960s, seated and multi-segmented thermal manikins were developed, and digital regulation was employed, allowing for much more accurate power application and measurement. Over time breathing, sneezing, moving (such as continuous walking or biking motions) and sweating were all employed in the manikins, in addition to male, female, and child sizes depending on the application. Nowadays most manikins used for research purposes will have a minimum of 15 zones, and as many as 34 with options (often as a purchasable add-on to the base manikin) for sweating, breathing, and movement systems although simpler manikins are also in use in the clothing industry. Additionally, in the early 2000s several different computer models of manikins were developed in Hong Kong, the UK, and Sweden. The following table gives an overview of different thermal manikin developments through the years:

Design

Modern thermal manikins consist of three main elements, with optional additional add-ons. The exterior skin of the manikin may be made of fiberglass, polyester, carbon fiber, or other heat conducting materials, within which are temperature sensors in each measurement zone. Underneath the skin is the heating element. Each zone of a thermal manikin is designed to be heated as evenly as possible. To achieve this, wiring is coiled throughout the interior of the manikin with as few gaps as possible. Electricity is run through the wire to heat it, with the power use of each zone being separate controlled and recorded by the manikin control software. Finally, the manikins are designed to simulate humans as accurately as possible, and so any necessary additional mass is added to the interior of the manikin and distributed as needed. Additionally, manikins may be fitted with supplemental devices that mimic human actions such as breathing, walking, or sweating. The heating element of thermal manikins may be set up in one of three locations within the manikin: at the outer surface, within the skin of the manikin, or in the interior of the manikin. The further inside the manikin the heating element is, the more stable the heat output at the skin surface will be, however the time constant of the manikin’s ability to respond to changes in the external environment will also rise as it will take longer for heat to penetrate through the system.

Control The amount of heat supplied to thermal manikins may be controlled in three ways. In “comfort mode” the PMV model equation found in ISO 7730 is applied to the manikin, and the controller software calculates the heat loss an average person would be comfortable undergoing within a given environment. This requires that the system know several basic facts about the manikin (surface area, hypothesized metabolic rate) while experimental factors must be input by the user (clothing insulation, Wet Bulb Globe Temperature). The second control method is constant heat flux from the manikin. That is, the manikin supplies a constant level of power, set by the user, and the skin temperature of the different segments is measured. The third method is that the skin temperature of the manikin is maintained constant at a user-specified value, while the power increases or decreases depending on the environmental conditions. This may arguably be considered a fourth method as well, as one can set the entire manikin to maintain the same temperature in all zones, or choose specific temperatures for each zone. Of these methods, the comfort mode is considered to be the most accurate representation of the actual heat distribution across the human body, while the heat flux mode is primarily used in high temperature settings (when room temperatures are likely to be above 34 °C).

Calibration

Temperature sensors To obtain the most accurate results possible it is necessary to calibrate the internal temperature sensors of the thermal manikin. A good calibration will use at least 2 temperature set points minimum 10 °C apart from one another. The manikin is set up in a thermally controlled environmental chamber so that the temperature of all its segments will be nearly identical to the operative temperature of the chamber. This means that the manikin must be unclothed and with minimal insulation between any body part and the air. A good system to achieve this is to have the manikin seated in an open chair (allowing air movement to pass through), with its feet propped up off the ground. Fans should be used to increase air movement in the chamber, ensuring constant mixing. This is acceptable for maintaining a constant temperature as there is no evaporative cooling without sweating or condensation (humidity should be low to ensure no condensation occurs). At each temperature set point the manikin will need to remain in the room for 3 to 6 hours in order to come to steady state conditions. Once equilibrium has been obtained a calibration point may be obtained for each body segment (this should be included in the control software).

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Thermal manikin

Start with the simplest possible case. Write down what Thermal manikin claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Thermal manikin before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Thermal manikin ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Thermal manikin

In research: Thermal manikin appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Thermal manikin in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Thermal manikin is common in secondary-school and first-year university syllabi. It links to neighbouring topics Heat transfer, Heating, ventilation, and air conditioning, Temperature, so understanding it makes those chapters shorter.
In everyday life: Look for Thermal manikin outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Thermal manikin in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Thermal manikin means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Thermal manikin out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Thermal manikin in simple terms?

Why does Thermal manikin matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Thermal manikin?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Thermal manikin.