# Experimental Investigation into the Thermal Performance of Personal Cooling Mechanisms
## 1 Introduction
### Methods for Characterisation of Cooling Garments  
In the literature, various testing methods are utilised to characterise cooling garments. These methods include mathematical calculation models or standardised test methods such as ASTM F2371-24 [18], which employs a thermal manikin, and the standard ASTM F2300-22 [19], which involves human subjects. The following section describes the methods used for characterising cooling garments:  
* Thermophysiological prediction models: Thermophysiological comfort models can be categorised into single-node, two-node, and multi-node models, depending on how the body is divided for simulation purposes. The single-node predictive model considers the complete body, while the two-node and multi-node models break the body into different parts [20]. [PERSON]'s PMV (Predicted Mean Vote) model was the first classical single-node thermal comfort model [21]. This model is based on a combination of physical environmental factors and human physiological factors, establishing a linear relationship between mean skin temperature, perspiration rate, and activity intensity, but it applies only under uniform conditions. In the two-node model, which simplifies the human body into two layers, skin and core, the most used comfort model is from [PERSON] et al. [22]. Multi-node models include the Stolwijk model [23], which is designed only for steady-state conditions, and the [PERSON] et al. [24] model, which applies to steady-state, transient, and non-uniform conditions. Several recent models have enhanced existing frameworks, such as the JOS-2 [25] and JOS-3 [26], which build upon the foundational Tanabe model. Furthermore, notable improvements have been made to the Stolwijk model, including integrating the [PERSON] et al. model [27; 28] and the UC Berkeley Thermophysiological Comfort model [29; 30]. Another thermoregulation model, THERMODE 23 (Thermoregulation Model for Disuniform Environments) [31], was recently introduced. This model thoughtfully incorporates the latest advancements in both active and passive systems, as well as advancements in the modelling of thermal sensation. The use of thermophysiological models provides quick results and allows the assessment of various combinations using estimated data to predict human thermal responses. However, a limitation of these models is that they yield simulations rather than precise measurements, and exceptions must be considered such as the type of activity, age, and race, among other parameters.
* Standard method according to ASTM F2371-24: This testing method uses a thermal manikin to evaluate the cooling power and duration of a cooling vest. It measures the heat needed to maintain the mean skin temperature of the manikin, but it does not assess thermophysiological parameters.
* Standard method according to ASTM F2300-22: This method involves conducting tests with individuals to understand their physiological responses, comfort levels, and thermal sensations while wearing the garment. Additionally, specific test methods with human subjects have been developed by individual laboratories to suit the particular use of the garment; for instance, [PERSON] et al. [32] examined a vest with a fluid circulation system, while [PERSON] and [PERSON] [33] tested the thermal comfort of firefighting suits with different types of vests.