The log mean temperature difference (LMTD) is used to determine the heat transfer rate in a heat exchanger because: a. The heat transfer coefficients for the hot and cold fluid vary with position b. The temperature difference between the hot and cold fluids varies with position c. The flow rates of the two fluids are different Explain why counterflow heat exchangers have a better performance than parallel heat exchangers. The hot and cold inlet temperatures to a concentric tube heat exchanger are 240C and 100C, respectively. The hot and cold outlet temperatures are 130C and 145C, respectively. Is the heat exchanger operating in a parallel flow or in a counterflow configuration? Explain. (3 pts)