Performance investigation of a novel calorimeter for a heat pump system according to flow loops

Abstract

Heat pumps cover a wide range of heating and cooling applications owing to their means of drawing out heat from ground, air and water at low temperature. In order to acquire performance data for heat pump certification and rating, the calorimeter is used in measuring the heat pump. In conventional approach of measuring the heat pump with standard test conditions, a great amount of energy is used in the calorimeter for cooling and heating. Using innovative ways to enhance the calorimeter performance is significant for energy and cost savings. Therefore, a novel calorimeter was developed for heat pump measurement. Two different flow loop configurations, specified as cases (1) and (2) were adopted. In the case (1), secondary fluid flow through the heat recovery unit was directly from heat pump test unit heat exchanger while in case (2), secondary fluid flow through heat recovery unit was from constant temperature water bath directly. The energy usage of the novel calorimeter based on the impact of each configuration was analyzed. Experiments were conducted using a water-to-water heat pump unit in heating and cooling approach with variation in operating conditions. Energy analyses based on test data indicated that energy reduction of the novel calorimeter was at least 72 % for heating and 69 % for cooling in relation to energy used in conventional calorimeter. Moreover, for novel calorimeter, case (1) resulted in energy savings of at least 9.1 % for cooling and 13 % for heating in relation to case (2). However, for heat pump units with very low capacities, tests measurements were executed using case (2) configuration because the tests in case (1) resulted in large thermal fluctuations such that the steady operating conditions of the water setpoint temperatures at inlet to the indoor and outdoor heat exchangers of the test unit were unattainable.