Yasuki Hirota

Performance prediction method for a multi-stage Knudsen pump

In this study, the novel method to predict the performance of a multi-stage Knudsen pump is proposed. The performance prediction method is carried out in two steps numerically with the assistance of a simple experimental result. In the first step, the performance of a single-stage Knudsen pump was measured experimentally under various pressure conditions, and the relationship of the mass flow rate was obtained with respect to the average pressure between the inlet and outlet of the pump and the pressure difference between them. In the second step, the performance of a multi-stage pump was analyzed by a one-dimensional model derived from the mass conservation law. The performances predicted by the 1D-model of 1-stage, 2-stage, 3-stage, and 4-stage pumps were validated by the experimental results for the corresponding number of stages. It was concluded that the proposed prediction method works properly.

Development of a Compact Adsorption Heat Pump System for Automotive Air Conditioning System

Adsorption heat pump (AHP) system is one of the key technologies. We have been developing AHP system utilizing the exhaust heat from the engine coolant system, which can meet the requirements in the automotive application. However, AHP systems have not been used in automotive applications because of its low volumetric power density of the adsorber. In order to improve the volumetric power density of the adsorber, we suggest a compact adsorber which is characterized by honeycombed composite plates of an adsorbent with thermal conductive filler bonded to a plate-type heat exchanger. In the suggested adsorber, the adsorption and desorption rate and the packing density were 1.33 times and 1.36 times larger than a reported coating-type adsorber respectively. The volumetric power density of our adsorber is comparable to that of an mechanical compressor for on board air conditioning system. The developed compact adsorber can contribute to reducing the size and total cost of the AHP system. This technology is to be applicable to the AHP systems not only for automotive application, but also for large-scale air conditioning systems (e.g. factory air conditioning system).