13-05-2022, 01:07 PM
Cool pictures ? hopefully made more informative with a bit of theory to muse over.
Heat exchangers have two properties of interest, efficiency and effectiveness. In heat exchanger terminology the effectiveness is a measure of the temperature change through a stage compared to the maximum change possible, so if the water enters the top hot and exits the bottom at room temperature (like the early photos) its running at 100% effectiveness. (probably due to slow flow flow and a cold radiator). In a thermosyphon system flow will increase - increasing the efficiency and decreasing the effectiveness until a balance is reached where the heat exchanged is equal to the heat provided by the engine.
On cold days the balance will be such that the hot side does not get very hot so you have two options, fit a thermostat or reduce the efficiency of the radiator by blocking off a portion. The difference being in the former the effectiveness with the reduced flow will be high and you will have colder coolant entering the block and in the latter you wont, but you have less control of the temperature of the hot side. Not saying thermostats are bad, but in modern cars this problem is controlled by bypassing \ mixing rather than allowing cold radiator water enter the block directly.
Heat exchangers have two properties of interest, efficiency and effectiveness. In heat exchanger terminology the effectiveness is a measure of the temperature change through a stage compared to the maximum change possible, so if the water enters the top hot and exits the bottom at room temperature (like the early photos) its running at 100% effectiveness. (probably due to slow flow flow and a cold radiator). In a thermosyphon system flow will increase - increasing the efficiency and decreasing the effectiveness until a balance is reached where the heat exchanged is equal to the heat provided by the engine.
On cold days the balance will be such that the hot side does not get very hot so you have two options, fit a thermostat or reduce the efficiency of the radiator by blocking off a portion. The difference being in the former the effectiveness with the reduced flow will be high and you will have colder coolant entering the block and in the latter you wont, but you have less control of the temperature of the hot side. Not saying thermostats are bad, but in modern cars this problem is controlled by bypassing \ mixing rather than allowing cold radiator water enter the block directly.