EFFECT OF PRE-COOLED INLET GAS ON TEMPERATURE EVOLUTION DURING REFUELLING

Manufacturers of the automotive industry (Toyota, Honda, General Motors…) have established 2015 as the starting year for the introduction of commercial Fuel Cell Vehicles (FCV) in the Japanese, European and USA markets. To have a successful introduction of these FCVs, a network of hydrogen stations should be deployed. These hydrogen stations have to accomplished several safety requirements, i.e. not to reach a temperature higher than 85°C in the gas inside the tank during the refuelling. This temperature limit of 85°C is set for two reasons, to protect the materials of the tank from thermal degradation, and to be able to fill the tank (100% state of charge) without surpass the maximum working pressure (125% of the nominal working pressure). In addition, refuelling time shouldn't exceed 3-5 minutes, to be competitive with the conventional petrol stations and attractive for the potential costumers. To perform a refuelling within these two limits represents a technological challenge, since the faster the filling the higher the increase of temperature (this increase is even higher in a 70 MPa tank). For this reason it is necessary to study this process and try to figure out which are the important parameters in the temperature evolution during refuelling. The JRC-IET has developed a facility, GasTeF, for carrying out tests on full-scale high pressure vehicle’s tanks for hydrogen or natural gas. This facility is unique in Europe and it allows performing permeation tests and fast filling tests at a maximum pressure up to 850 bars (with helium or hydrogen). The facility allows performing test with different environmental temperatures, flowing rates and temperatures gas inlet. A big amount of data is collected during the tests thanks to the different sensors installed in the facility. In this paper we are going to show the effects of pre-cooled inlet gas on temperature evolution, depending on several parameters as type of tank or flow rate. The type of tank (metallic liner, type 3 or plastic liner, type 4) affects to temperature evolution during the filling, being reached lower temperatures in type 3 tanks due to their higher heat transfer coefficient. This different thermal behaviour implies different pre-cooling needs depending on the type of tank, which are studied and included in this paper. The flow rate plays an important role in the temperature evolution during a refuelling, being higher the temperature increase of the gas inside the tank with higher flow rates. The importance of the pre-cooling regarding the flow rate is considered in this study. The results of all the tests performed for the elaboration of this paper will be compared with the fuelling protocols shown in the SAE J2601, where several inlet gas temperatures (-40°C, -20°C, 0°C, and not pre-cooled gas) are considered. Previous studies have shown the need to pre-cool the gas to reach a 100% of state of charge in refuelling with a filling time of less than 5 minutes. A discussion comparing the energy used to cool down the gas with the extra amount of hydrogen mass introduced in the tank due to the pre-cooling is included in this study.

ORTIZ CEBOLLA Rafael;  DE MIGUEL ECHEVARRIA Nerea;  ACOSTA IBORRA Beatriz;  MORETTO Pietro;  BONATO Christian; 

2014-07-07

Spanish Hydrogen Association

JRC88002