板式與管殼式熱交換器之實驗研究

EXPERIMENTAL STUDIES ON PLATE AND SHELL-AND-TUBE HEAT EXCHANGERS

本研究旨在以實驗的方法探討板式與管殼式熱交換器之熱傳特性與比較，建立一套具有冷、熱恆溫槽之實驗量測系統，經由循環泵引流經過測試的熱交換器，藉由量測熱交換器的進出口溫度以及熱力與熱傳的公式計算出總體熱傳係數。根據實驗的觀察與分析，與具平滑圓管之管殼式熱交換器比較起來，板式熱交換器於達穩態所需之時間顯然比較長。單殼雙通道的管殼式熱交換器中，熱、冷流體在進口的相異端（Case I）時，其熱傳效果優於熱、冷流體在進口之同一端（Case II），此外，實驗結果顯示Case I流動布置的熱交換器之總體熱傳係數大於Case II約13%。於板式熱交換器方面，反向流板式熱交換器熱傳效果較佳，然而由於本實驗所使用的板式熱交換器規模較小，其流動長度亦較短，反向流的總體熱傳係數僅約大於平行流的總體熱傳係數約2.68%。此外，無論流體流動布置的方式為何，板式熱交換器之總體熱傳係數皆優於管殼式熱交換器之總體熱傳係數。 This study mainly investigates the heat transfer characteristics and comparison of plate and shell-and-tube heat exchangers by experimental methods. A set of experimental measurement sys-tem with cold and hot constant-temperature reservoirs is set up. The tested heat exchangers are de-signed to be passed through the circulation pumps. The overall heat transfer coefficient is calculated by the measured temperatures of the inlets and outlets of the tested exchangers and formula of thermodynamics and heat transfer. According to the observation and analysis of the experimental data, compared with the shell-and-tube heat exchanger with a smooth round tube, the time required for the plate heat exchanger to reach the steady state is obviously longer. In the shell-and-tube heat exchanger, with the arrangement of the hot and cold fluids at the different end of the inlet (Case I), the heat transfer effect is superior to the heat and cold fluid at the same end of the inlet (Case II). The experimental results show that the overall heat transfer coefficient of the heat exchanger for Case I is greater than that for Case II by about 13%. As for plate heat exchangers, the counter-flow plate heat exchanger has better heat transfer than the parallel-flow one. However, since the plate heat exchanger used in this experiment is small in scale, its flow length is a little short. The overall heat transfer coefficient of the heat exchanger with counter flow is only about 2.68% greater than that with parallel flow. Furthermore, regardless of the flow arrangement, the overall heat transfer coefficients of the plate heat exchangers are superior to those of the shell-and- tube heat exchangers.