Cooling efficiency of vests with different cooling concepts over 8-hour trials

Figures & data

Table 1. Basic information of the cooling vests, categorised according to the cooling concept used.

No.	Cooling concept	Code	Cooling vest	Size†	Company	Coolant	PCM Tm (°C)*	Total weight (kg)
1	Active vests	COMP	CompCooler UniVest ICE Cooling System with 2L detachable Bladder	XS/S	Battery Heated Clothing, Navajo Blvd. Pahrump, NV, US	Water-circulation	N/A	3.064
2		VRTX	Vortex Cooling/Heating Vest	M/L	Allegro Industries Shiloh Church Rd., Piedmont, SC, US	Compressed air ventilation	N/A	1.054
3	Evaporative vests	ECOOL	Cool Shirt SX3	L	E.Cooline, pervormance international GmbH, Mühlsteige, Ulm, DE	Water (soaked)	N/A	1.051
4		IH wet	Inuteq Bodycool Hybrid, no inserts	S	INUTEQ International B.V., Zweedsestraat, Deventer, NL	Water (soaked)	N/A	0.813
5		IZI	IZI Hydrogel 02	S/M	IZI BodyCooling.com B.V., Nieuwe Holleweg, Beek – Ubbergen (Gld), NL	Water (soaked) + gel (embedded)	N/A	1.106
6		SMART	Inuteq Bodycool Smart	S	INUTEQ International B.V., Zweedsestraat, Deventer, NL	Water (filled)	N/A	0.503
7		TECH	Techniche Evaporative Cooling Kewlshirt Tank Top	L	Techniche Llc., Pioneer Avenue, Vista, CA, US	Water (soaked)	N/A	0.844
8		XTREM	Inuteq Bodycool Xtreme	S	INUTEQ International B.V., Zweedsestraat, Deventer, NL	Water (soaked)	N/A	0.390
9	Vests with PCM and gel inserts	CRYO	CryoVest Sport	M	BMedical Pty Ltd, Fortitude Valley, QLD, AU	Gel inserts	∼ 0**	1.675
10		ERGO	Chill-Its 6235 Standard Phase Change Cooling Vest	S/M	Ergodyne, 1021 Bandana Blvd. East, Suite Saint Paul, MN, US	PCM inserts	18	1.824
11		FICE	Cooling Vest for Cooling Inserts, Standard, Feather ice inserts	L	Allegro Industries, Shiloh Church Rd., Piedmont, SC, US	Silica-crystals inserts	No data available	2.005
12		FLEX	FlexiFreeze Ice Vest - Zipper front	Unisize	Maranda Enterprises, Llc, W. Donges Bay Rd Mequon, WI, US	Ice inserts	0	1.748
13		GTEK	Sports Cool Vest, Non-toxic cooling packs	Unisize	Glacier Tek, Park Glen Road, Minneapolis, MN, US	PCM inserts	15	2.208
14		IH 6.5	Inuteq Bodycool Hybrid, PCM Coolpack 6.5 °C	S	INUTEQ International B.V., Zweedsestraat, Deventer, NL	PCM inserts	6.5	1.467
15		IH 15	Inuteq Bodycool Hybrid, PCM Coolpack 15 °C	S	"	PCM inserts	15	1.491
16		IH 21	Inuteq Bodycool Hybrid, PCM Coolpack 21 °C	S	"	PCM inserts	21	1.460
17		IH 29	Inuteq Bodycool Hybrid, PCM Coolpack 29 °C	S	"	PCM inserts	29	1.422
18		POLAR	Adjustable Poncho Cooling Vest, Kool Max Packs	Unisize	Polar Products Inc., Cavalier Trail Stow, OH, US	Gel inserts	No data available	2.229
19		STA	StaCool Industrial Vest	Unisize	StaCool Industries, Inc., Ave Ocala, FL, US	Gel inserts	No data available	3.111
20	Hybrid vests	IH 6.5 wet	Inuteq Bodycool Hybrid, PCM Coolpack 6.5 °C, wet	S	INUTEQ International B.V., Zweedsestraat, Deventer, NL	Water (soaked) + PCM inserts	6.5	1.933
21		IH 15 wet	Inuteq Bodycool Hybrid, PCM Coolpack 15 °C, wet	S	"	"	15	1.927
22		IH 21 wet	Inuteq Bodycool Hybrid, PCM Coolpack 21 °C, wet	S	"	"	21	1.920
23		IH 29 wet	Inuteq Bodycool Hybrid, PCM Coolpack 29 °C, wet	S	"	"	29	1.843

*PCM Tm (°C): Melting temperature of the phase change material in the inserts.

**The main ingredient of the gel inserts is water (82.76 %), therefore their melting temperature is expected to be at approximately 0 °C.

†Manufacturer’s recommendations based on the dimensions of the manikin.

Figure 1. Graphic presentation of the parameters determined in the cooling capacity measurements. Pmax: maximal cooling power; T_c: cooling duration when P ≥ 20 W·m⁻²; AUC: area under the curve, indicating cooling capacity.

Cooling power in units of Watts per square metre over an 8-h period. The graph demonstrates a decrease in cooling power from a maximum value of 65 W·m−2 to the cooling efficiency threshold of 20 W·m−2 within 3.5 h, which is defined as the cooling duration. The cooling capacity is represented by the area under the cooling power curve over cooling duration period (the time during which the cooling power is above 20 W·m−2).

Figure 2. Cooling power of vests within each category over 8-h trial.

Four graphs plotting cooling power of all tested vests over an 8-h period. Each graph presents vests within the same category according to their cooling concept (active vests, evaporative vests, vests with PCM and gel inserts and hybrid vests).

Table 2. Cooling capacity of the tested cooling vests.

	Vest	Pavg (W·m^-²)	Pmax (W·m^-²)	tc (min)	AUC (W·h·m^-²)
Active vests	VRTX	41	44	∞	331
	COMP	17	60	151	118
Evaporative vests	*IH	17	42	210	113
	XTREM	14	37	178	97
	TECH	22	43	188	97
	ECOOL	18	43	141	74
	IZI	17	24	45	17
	SMART	4	6	0	0
Vests with PCM and gel Inserts	STA	23	65	210	164
	FLEX	14	80	116	101
	POLAR	16	40	188	99
	CRYO	13	73	110	90
	GTEK	13	39	177	90
	FICE	11	92	85	75
	ERGO	10	38	122	66
	IH 6.5	7	42	82	43
	IH 15	7	28	93	37
	IH 21	6	21	21	7
	IH 29	5	16	0	0
Hybrid vests	IH 15 wet	21	75	198	146
	IH 21 wet	22	68	203	146
	IH 6.5 wet	22	88	194	145
	IH 29 wet	20	57	226	127

P_avg: average cooling power throughout the 8-h measurement; P_max: maximal cooling power; t_c: cooling duration when P ≥ 20 W·m^-2; AUC: area under the curve of the P(t_c) graph, indicating cooling capacity of each cooling vest. Within each category the vests are ranked from the largest to the smallest AUC. *IH without PCM inserts.

Table 3. Thermal resistance of the tested cooling vests.

	Condition	Rt (°C·m^2·W^-1)	Rt (%)
Control	Clothing ensemble	0.199	100
Active vests	VRTX	0.266	133
	COMP	0.325	163
Evaporative vests	XTREM	0.201	101
	SMART	0.224	112
	IZI	0.231	116
	ECOOL	0.244	123
	TECH	0.249	125
	*IH	0.275	138
Vests with PCM and gel inserts	ERGO	0.225	113
	GTEK	0.227	114
	FICE	0.237	119
	POLAR	0.239	120
	FLEX	0.254	127
	CRYO	0.256	128
	IH 15	0.260	130
	STA	0.290	146

Rt: Total thermal resistance (baseline clothing ensemble + cooling vest); Rt (%): Rt of each condition expressed relative to the control – values over 100 indicate greater Rt compared to control condition. Within each category the vests are ranked from the smallest to the largest relative Rt. *IH without PCM inserts.

Table 4. Relative evaporative resistance (Re; %) of the activated cooling vests.

	Condition	Re (%)
Control	Clothing ensemble	0
Active vests	COMP	19
	VRTX	−4
Evaporative vests	SMART	15
	IZI	15
	TECH	29
	ECOOL	33
	XTREM	39
	*IH	40
Vests with PCM and gel inserts	IH 6.5	6
	GTEK	8
	IH 29	9
	IH 21	14
	IH 15	14
	POLAR	15
	CRYO	16
	ERGO	17
	FICE	17
	FLEX	20
	STA	21
Hybrid vests	IH 29 wet	28
	IH 21 wet	32
	IH 15 wet	34
	IH 6.5 wet	40

During all conditions the wet skin was donned directly on the manikin simulating sweating; Re (%): evaporative resistance of each activated cooling vest, expressed relative to the Re of the control condition – values over 0 indicate greater Re compared to control condition (reduced evaporation of water from the skin), whereas values below 0 indicate lower Re compared to control condition (increased evaporation of water from the skin). Within each category the vests are ranked from the lowest to the greatest relative Re. *IH without PCM inserts.